A platinum source reagent liquid solution, comprising: (i) at least one platinum source compound selected from the group consisting of compounds of the formulae: (A) RCpPt(IV)R'.sub.3 compounds, of the formula: ##STR1## wherein: R is selected from the group consisting of hydrogen, methyl, ethyl, i-propyl, n-propyl, n-butyl, i-butyl, t-butyl, trimethylsilyl and trimethylsilyl methyl; and each R' is independently selected from the group consisting of methyl, ethyl, i-propyl, n-propyl, n-butyl, i-butyl, t-butyl, trimethylsilyl and trimethylsilyl methyl; and (B) Pt(.beta.-diketonates).sub.2 of the formula: ##STR2## wherein: each R" is independently selected from the group consisting of methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, trifluoromethyl, perfluoroethyl, and perfluoro-n-propyl, and (ii) a solvent medium therefor. The platinum source reagent liquid solutions of the invention are readily employed in a chemical vapor deposition process system including a liquid delivery apparatus for volatilizing the source reagent liquid solution and transporting the resulting vapor to the chemical vapor deposition reactor for deposition of platinum on a substrate mounted in the CVD reactor.