A process has been developed for preparing a Fischer-Tropsch catalyst precursor and a Fischer-Tropsch catalyst made from the precursor. The process includes contacting a gamma alumina catalyst support material with a first solution containing a vanadium compound and a phosphorus compound, to obtain a modified catalyst support material. The modified catalyst support material is calcined at a temperature of at least 500° C. The modified catalyst support is less soluble in acid solutions than an equivalent unmodified catalyst support. The modified catalyst support loses no more than 6% of its pore volume when exposed to water vapor. The modified catalyst support is contacted with a second solution which includes a precursor compound of an active cobalt catalyst component to obtain a catalyst precursor. The Fischer-Tropsch catalyst has enhanced hydrothermal stability as measured by losing no more than 10% of its pore volume when exposed to water vapor.