A diffusive transport relaxation technique has been developed to study the chemical processes occurring during laser-induced chemical vapor deposition. The technique is based on modulation of the laser light intensity which results in a modulation of the surface reaction rate. This perturbation of the reaction rate produces transients in the gas-phase reactant and product concentrations for the case of gas-phase transport-limited deposition. Product species can be differentiated from species formed from the reactant during ionization and fragmentation due to the phase-sensitive nature of the detection scheme. The system response is examined theoretically by describing the response of the surface reaction rate to the modulated laser light and then examining the response of the gas-phase reactant and product concentrations to the modulated surface reaction. The technique was used to identify the gaseous products formed during laser-induced deposition of gold using dimethyl gold hexafluoroacetylacetonate.