There is provided a process for renewing the activity of supported metal catalysts for the hydrogenation of carbon monoxide to form a mixture of hydrocarbons comprising decreasing the hydrocarbon content of the catalyst, preferably by contact with hydrogen-containing gas at elevated temperatures, impregnating under a non-oxidizing atmosphere with a solution of at least one of an ammonium salt and an alkyl ammonium salt, optionally in combination with up to five moles of ammonia per liter of solution to the point where it has absorbed a volume of solution equal to at least about 10% of its calculated pore volume; oxidizing the catalyst with a gaseous oxidant in the presence of the impregnating solution and activating the catalyst by reduction with hydrogen at elevated temperatures. Optionally, the catalyst is calcined after the oxidation step, and passivated after the activation step.