Palladium nanoparticles were synthesized in aqueous medium via reduction by hydrazine using various polymers (polyvinylpyrrolidone and polystyrene sulfonate) and the clay mineral hectorite as stabilizers. The kinetics of homogeneous and heterogeneous nucleation processes was studied by UV-visible spectrophotometry. The effect of the polymer and concentration of the silicate and palladium ions on particle formation rate was investigated. The size of the nanoparticles were determined by transmission electron microscopy. Both polymers and the silicate lamellae were found to be capable of stabilizing the particles. The rate of reduction is decreased by increasing amounts of stabilizing agents and increased by increasing concentrations of precursor ions. The kinetics of heterogeneous nucleation was determined by the adsorption of the palladium species at the clay mineral particles and the viscosity of the hectorite dispersion.