Phase formation stages of MgWO4 and ZnWO4 (precursor compositions for following steps) were investigated by monitoring the reactions of oxide chemicals at various temperatures. Developed phases were examined by using X-ray diffraction (XRD). Successive attempts were also conducted for Pb(Mg1/2W1/2)O-3 (PMW) and Pb(Zn1/2W1/2)O-3 (PZW) by reacting PbO with the precursor compounds. Stages of phase development in the two compositions were also analyzed. The results are compared with those of another tungsten-containing perovskite Pb(Fe2/3W1/3)O-3 (PFW) and its B-site precursor Fe2WO6. After PbO addition to the precursor powders, a perovskite phase formed directly (i.e., without any intermediate phases) in the case of PMW. For PbO + 1/2ZnWO(4), in contrast, the decomposition of ZnWO4 and preferential reaction with PbO resulted in Pb2WO5 and ZnO, instead of the perovskite PZW.