The reduction of CdSO4, {Pd-3[SSP(OC2H5)(2)](Ph3P)(2)S-2}, CuCl, and CuSO4 has been investigated using pulse and gamma radiolysis technique in water-in-oil microemulsion. Rate constants for the reduction of these compounds by e(-)(aq) were found to be muck lower, compared to those for the same compounds in aqueous solution. The bimolecular rate constants were correlated with the "water-pool" size, location of the compounds, and surrounding environment. After the compounds were bombarded by a large number of electron pulses, the formation of colloidal Cd, Cu, and Pd was observed. The formation of colloidal Cu was faster in the case of CuCl than in that of CuSO4. Morphologies of colloidal Cd and Pd were determined by electron microscopy