Quantum chemical calculations were performed using density functional theory to study interactions of C-1 and C-2 hydrocarbons with 10-atom Pt clusters. The heats of ethylene adsorption to form di-sigma- and pi-adsorbed species were calculated to be -171 kJ/mol and -103 kJ/mol, respectively, at 298 K. The calculated heat is -109 kJ/mol for the formation of ethylidyne species from ethylene adsorption, with the formation of gas phase dihydrogen at 298 K. The heat of adsorption of acetylene to form molecular di-sigma/pi-adsorbed species is -209 kJ/mol, and the heat of formation of di-sigma/pi vinylidene species is -278 kJ/mol at 298 K. The calculated structural parameters of these species agree with the available experimental data. The same 10-atom platinum cluster is used to calculate the heats of adsorption of various other hydrocarbon species which may be reactive intermediates for hydrocarbon conversion reactions. These species include vinyl, methyl, ethyl, methylene, ethylidene, and ethylylidene species.