Hydrogen is often envisioned as a green fuel and energy carrier. However, a greenhouse gas-free production method is still needed for this purpose. A promising method is the pyrolysis of methane. Here, we present the 3-dimensional simulation of methane pyrolysis in a microwave plasma torch operated in an argon-methane mixture. Due to the high gas temperatures, the chemistry is dominated by reactions between neutral particles. Therefore, the plasma is only treated as a heat source using space-resolved gas temperature measurements as input. The end-of-pipe results of the simulation are compared to measured values, showing good agreement for methane conversion.