A process for preparing a cobalt-containing hydrocarbon synthesis catalyst precursor includes calcining a loaded catalyst support comprising a catalyst support supporting a cobalt compound. The calcination includes subjecting the loaded catalyst support to heat treatment by heating the loaded catalyst support to a temperature, T, of at least 220° C. at a heating rate below 10° C./minute, and effecting gas flow at a space velocity of at least 9 m3n/kg cobalt compound/hour over the loaded catalyst support during at least part of the heating. The cobalt-containing hydrocarbon synthesis catalyst precursor is thereby produced.