Highly dispersed, unsupported Pt, Pd, Rh, and bimetallic Rh/Pt and Pt/Pd clusters were produced by laser ablation using a KrF excimer laser operating at power densities up to 1.9 GW/cm(2). By the evaporation of two metals simultaneously, bimetallic clusters with variable stoichiometric composition were obtained, depending on buffer gas, buffer gas pressure, and the deposited laser energy. The ablation was carried out in a glass cell under a continuous gas flow or in a UHV system with a static gas atmosphere. The pressure ranged from 5 to 100 Torr. Emission spectra of the plasma plume were taken for detection of ions acid highly excited atoms in order to study the temporal evolution of the ablation process. The expansion of the plasma plume was imaged with a CCD camera at different times after the laser pulse. In the first few nanoseconds, the expansion velocity reached values up to 3.5 x 10(6) cm/s. Characterization of the metal clusters by XPS showed that samples produced in the glass reactor are highly contaminated with carbon up to 60 atom %. However, by using a UHV system, the carbon content was reduced to 14 atom %. Alloy formation in bimetallic Rh/Pt particles with a l-to-l atomic ratio of rhodium to platinum was verified by EXAFS spectroscopy. The coordination environment around platinum consists of both platinum and rhodium neighbors, 56 and 44 atom %, respectively, while rhodium appears to be coordinated predominantly to other rhodium atoms. These results are consistent with a bimetallic Rh/Pt cluster model whereby the cluster core is composed of rhodium atoms and the outer surface is formed by platinum atoms. Particle size and size distribution were analyzed by XRD, TEM, and BET isotherms. The particle diameters ranged from 2 to 20 nm, showing a linear dependence on buffer gas pressure and laser energy.