Perovskite Pb(Mg0.33Nb0.67)O-3 (PMN) was synthesized via an aqueous solution-gel route. A stable trimetallic aqueous precursor solution was prepared by combining a peroxo-citrato-Nb(V) complex with acetates of lead and magnesium at the appropriate pH. Evaporation of the water resulted in an amorphous gel, which was converted into the oxide phase by thermal decomposition of the gel structure. The preparation of the pure perovskite phase is hindered by the formation of a stable pyrochlore phase (Pb1.83Nb1.71Mg0.29O6.39) prior to the PMN crystallization. When a thermal shock heating technique was applied, pure perovskite PMN was obtained.