Catalytic Converter Metals: What's Actually Inside

A catalytic converter's value comes from three platinum-group metals coated onto its internal honeycomb: platinum, palladium, and rhodium. Each does a distinct chemical job in cleaning up exhaust, and none of them can simply be swapped for a cheaper substitute without redesigning the whole converter. Rhodium is the one that moves hardest in price — U.S. Geological Survey data shows its average annual price falling from over $20,000 a troy ounce to under $4,700 in the space of three years — and that volatility is a direct driver of why converters get stolen and why their scrap value swings so much.

What are the three metals inside a catalytic converter, and what does each one do?

Catalytic converters are built around a ceramic or metal honeycomb substrate, and that substrate is coated with a thin washcoat carrying tiny amounts of platinum-group metals. The U.S. Geological Survey describes the leading domestic use for these metals plainly: they're used as oxidation catalysts to treat automobile exhaust emissions, and the automotive industry has been the principal consumer of platinum-group metals since 1979.

The three that matter in a modern converter each handle a different reaction:

• Platinum and palladium are oxidation catalysts. They drive the chemical reactions that convert carbon monoxide (CO) and unburned hydrocarbons (HC) in the exhaust stream into carbon dioxide (CO2) and water vapor.
• Rhodium is the reduction catalyst. Its job is breaking apart nitrogen oxides (NOx) — a pollutant that oxidation reactions alone can't touch — back into harmless nitrogen and oxygen gas.

That three-metal split is what makes a modern converter a "three-way" catalyst: it's simultaneously running oxidation reactions (with platinum and palladium) and a reduction reaction (with rhodium) inside the same unit, on the same exhaust stream, at the same time. Older two-way converters, which only handled CO and HC oxidation, didn't need rhodium at all — it's the NOx reduction requirement that made rhodium a mandatory ingredient rather than an optional one.

The physical structure matters here too. The honeycomb substrate — usually a ceramic block, sometimes a corrugated metal foil in newer designs — exists purely to maximize surface area. Exhaust gas has to physically contact the metal coating to react, so a converter is engineered around thousands of narrow channels packed into a small cylindrical space, all coated with a washcoat layer that holds the platinum-group metal particles in place. The metal itself isn't a solid slug sitting inside the converter; it's a microscopically thin layer spread across that entire honeycomb surface, which is part of why the total weight of precious metal in any single converter is small relative to the metal's per-ounce value — a recycler isn't melting down a chunk of rhodium, they're assaying a ceramic brick for trace amounts of it.

Why can't manufacturers just use less rhodium, or swap it for something cheaper?

They do adjust the ratio, and it's one of the more interesting mechanics in this whole system. The USGS's most recent commodity summary notes that palladium has been substituted for platinum in most gasoline-engine catalytic converters because of palladium's historically lower price relative to platinum, and that about 25% of palladium can routinely substitute for platinum in diesel converters — as much as 50% in some applications. That substitution has real limits, though: palladium doesn't perform the same reduction chemistry rhodium does, so while platinum and palladium can trade places with each other to some extent, neither can fully replace rhodium's specific role in NOx reduction.

That's the metallurgical reason rhodium can't just be engineered out when its price spikes. A manufacturer can rebalance how much platinum versus palladium goes into the oxidation side of a converter based on which is cheaper that year, but the reduction side still needs rhodium, in some quantity, to meet emissions standards. Catalytic converters have been required on most 1975-and-newer passenger cars and light-duty trucks to meet federal emissions standards, a mandate the EPA's own historical timeline traces back to that model year, and rhodium's NOx-reduction role has been part of that requirement ever since three-way catalysts became standard.

Why does the amount of metal in a converter vary by vehicle?

Loading — how much of each metal goes into a given converter — isn't a fixed number across the industry, and it isn't something we're going to invent a figure for here, since neither the USGS nor the EPA publishes a standard per-vehicle loading table. What's documented instead is the shape of the variation: newer, larger, and higher-performance engines generally need more catalyst surface area and more precious metal to hit tighter emissions targets, while older or smaller engines under looser historical standards were built with less. A vehicle's emissions certification era, its engine displacement, and whether it runs one converter or two (common on V6 and V8 layouts) all shift how much total platinum-group metal is on board — which is also why theft targets skew toward hybrids and larger engines, since those tend to carry more metal per unit, not because of some universal per-car figure.

If you're trying to estimate what your specific car's converter might be worth, that's a different question from the metallurgy covered here — see how much of your car's value is the catalytic converter for what's actually knowable about that, and why no verified public figure applies evenly across every vehicle. A missing or aftermarket converter is also one of several condition factors a buyer weighs alongside things like dents, missing bumpers, or body damage — it changes the number, not whether the car sells.

Why has rhodium's price been so much more volatile than platinum's or palladium's?

This is the metal that makes converter theft economically attractive, and the USGS's own annual price data shows exactly why. Average annual rhodium prices reported by USGS moved as follows, in dollars per troy ounce:

That's a roughly 77% drop in rhodium's price from 2021 to 2024, followed by a partial rebound. Palladium fell over the same stretch too, but far less sharply in percentage terms, and platinum barely moved at all by comparison. The USGS commentary for 2026 attributes the more recent price increases — 24% for rhodium and 11% for palladium in the most recent year measured — to decreased production and increased demand, "particularly for rhodium in the hard disk and chemical catalyst industries and owing to the substitution of platinum in automobile catalysts."

Rhodium's volatility comes down to a supply problem platinum and palladium don't share as severely: it's mined almost entirely as a byproduct of platinum and palladium mining, concentrated overwhelmingly in South Africa and Russia, with essentially no dedicated rhodium mines anywhere in the world. When platinum and palladium mining output shifts for reasons that have nothing to do with rhodium demand — labor disruptions, energy shortages, a mining company scaling back palladium operations — rhodium supply moves with it regardless of what rhodium itself is doing in the market. A small, inelastic supply meeting industrial demand that can't easily substitute away from it is a textbook setup for the kind of price swings the USGS numbers show.

Does that price swing actually drive converter theft?

Directly, yes, though rhodium's price is only part of the picture — the ease of the theft itself matters just as much. A converter bolts onto the underside of a car with a small number of accessible fasteners, and cutting it free takes a battery-powered saw and well under a minute for someone who's done it before. That low barrier to entry, combined with a part that concentrates real dollar value into a few pounds of metal, is why New York has seen the theft numbers it has. Governor Hochul's office reported that New York City catalytic converter thefts nearly quadrupled in 2022, with 5,548 thefts recorded by mid-August that year compared to 1,505 over the same period in 2021, and Nassau County saw a 248% increase over the same window. That's what led New York to classify converters as a "major component part" requiring dismantlers to log and report what they take in.

If your own converter has already been taken, the metallurgy here isn't going to change what happened — is the car still worth anything after a catalytic converter theft covers what your options actually look like from there.

Does any of this metal actually get recycled?

Yes, and at meaningful scale. The USGS reports that roughly 140,000 kilograms of palladium and platinum were recovered globally from new and old scrap in a recent year, including about 50,000 kilograms of palladium and 8,600 kilograms of platinum recovered specifically from automobile catalytic converters in the United States. That recycling stream is a real part of the global supply picture for these metals — it's one reason legitimate scrap and recycling channels for converters exist at all, separate from the theft problem covered above. If you're wondering whether it's legal to sell a used converter through those channels on its own, rather than as part of a whole car, is it legal to sell a used catalytic converter separately in NY covers what New York's law actually requires.

Where CashMyCarNY fits in

Whatever's happening with rhodium, palladium, and platinum prices this month doesn't change whether we'll buy your car — converter intact, aftermarket, or missing entirely. We're a licensed buyer across all 62 New York counties, and the condition of specific parts is something we factor into an offer, not a reason to turn a car away. If you're getting ready for pickup, our pre-pickup checklist covers what to have ready. Get an instant offer in about 60 seconds, no-haggle, with free towing and payment at pickup.

Quick answers

What three metals are inside a catalytic converter? Platinum, palladium, and rhodium. Platinum and palladium handle oxidation reactions (converting carbon monoxide and hydrocarbons), and rhodium handles the reduction reaction that breaks down nitrogen oxides.

Why is rhodium worth so much more than platinum or palladium? Rhodium is mined almost entirely as a byproduct of platinum and palladium mining, with no dedicated rhodium mines. That thin, inelastic supply meeting steady industrial demand — mainly from catalytic converters — is what drives its price far higher and far more volatile than the other two metals, according to USGS data.

Can manufacturers just remove rhodium to cut costs? Not without redesigning the converter's emissions performance. Platinum and palladium can substitute for each other to a degree, but neither performs rhodium's specific role in reducing nitrogen oxides, which is required to meet federal emissions standards.

Does every catalytic converter contain the same amount of metal? No. Loading varies by engine size, emissions certification era, and whether a vehicle uses one or two converters, which is why theft targets skew toward larger engines and hybrids rather than following one universal figure.

Is scrap catalytic converter metal actually recycled? Yes. USGS reports roughly 50,000 kilograms of palladium and 8,600 kilograms of platinum were recovered from U.S. automobile catalytic converters in a recent year, part of a larger global recycling stream for these metals.

Does converter metal value affect what CashMyCarNY offers for a car in a specific county? Metal prices are one factor among several in any offer, and they apply the same way statewide. Our Queens page has details on pickup in that borough specifically.