Relaxor Pb(Sc1/2Nb1/2)O-3 (PSN) thin films without pyrochlore phase were processed from the modified alkoxide solution precursors. The preparation of single phase PSN thin films has a narrow processing window due to the appearance of an undesirable pyrochlore phase and volatility of PbO. Thin film processing has been improved through selection of precursor solutions, heat treatment and optimized deposition-condition are optimized. Especially, the effects of Pt substrates seeded with additional layers upper of TiO2 and La0.5Sr0.5CoO3 are investigated through the scanning electron microscopy (SEM) scanning of film/electrode interfaces. Dielectric behaviors of sol-gel derived PSN thin films on two different substrates are observed. They show the evidence of relaxor-like behaviors, i.e. the temperature dependence of the dielectric constant at different applied frequencies. Films on the TiO2/Pt/TiO2/SiO2/Si substrates exhibit better dielectric properties, such as frequency saturation over transition temperature and much lower dielectric loss than those on the La0.5Sr0.5CoO3/Pt/TiO2/SiO2/Si substrates. The differences of transition behaviors between PSN thin films and bulk ceramics are also discussed in relation to the processing temperature, interface phenomena between film and electrode, relatively small thickness and strain effect of films.