The liquid phase hydrogenolysis of methyl formate has been studied in a three phase slurry reactor using a Girdler G-89 copper chromite catalyst. Measurements at 446 K show a very high selectivity to methanol. The reaction is first order in methyl formate, first order in hydrogen for pressures of 1.7 to 4.5 MPa and has an apparent activation energy of 62 kJ mol-1. Unlike the corresponding vapour phase process at atmospheric pressure, the liquid phase reaction shows no evidence of catalyst deactivation at 450 K and to conversions beyond 70%. However, inhibition, which is at least partially reversible, becomes apparent at 473 K when carbon monoxide is detectable as a by-product. Inhibition can be observed at lower temperatures if carbon monoxide is deliberately introduced at pressures above 0.1 MPa. The apparent reaction order in carbon monoxide is then -0.32.