Ca 3-x Pb xNb 2O 8 and (Pb 1-x M x) 2Nb 2O 7 (M = Sr, Ba, Ca) solid solutions have been synthesized and identified by x-ray diffraction, their isomorphic capacity has been assessed theoretically, and the theoretical predictions have been compared with experimental data. The formation kinetics and mechanisms of the alkaline-earth-doped lead niobates have been analyzed in detail. The electrical conductivity of the synthesized niobates has been measured, and their chemical stability in acid solutions has been shown to be rather high. © Nauka/Interperiodica 2006.