Supported molybdenum catalysts are uniquely suitable for a number of reactions, notably the metathesis reaction between hydrocarbons with terminal double bonds. Heterogeneous catalysis offers advantages over homogenous routes with respect to catalyst recycling and separation. A way to produce extremely highly dispersed Mo-metal particles on completely dehydroxylated surfaces from Mo(CO)(6) is described. The metal dispersion is found to depend on: metal loading - higher loading leads to lower dispersion and larger particles; initial dispersion of the precursor - a dry process by subliming the Mo(CO)(6) onto the support was found to give a lower metal dispersion than a wet impregnation process, starting from a pentane solution of Mo(CO)(6). A method for the determination of Mo-dispersion on highly activated alumina surfaces by CO chemisorption has been established.