A laboratory stirred autoclave reactor has been developed to operate at temperatures up to 375 degrees C and pressures of at least 170 atma. The performance of a commercial "high pressure" methanol synthesis catalyst, the so-called "zinc chromite" catalyst, has been characterized over a range of temperature from 300 to 375 degrees C, pressures from 68 to 174 atma, H-2/CO ratios from 0.5 to 2.0 and space velocities from 1500 to 10000 sL/kg(catalyst)-hr. Towards the lower end of the temperature range, methanol was the only significant product. At the highest temperatures, the methanol synthesis reaction was close to equilibrium. There were significant quantities of methane, dimethyl ether and olefins in the product at these temperatures. Formation of higher alcohols was insignificant, although small amounts of isobutanol were formed at the highest temperatures and pressures, with 10 mole percent CO2 in the feed gas.