The main features of the synthesis of (Pb1-x Sr x)2Nb2O7 and (Pb1-x Bax)2Nb2O7 pyrochlore solid solutions were determined using isothermal thermogravimetry in tandem with formal-kinetic analysis. The stability and electron-transport properties of the triple niobates were studied, which allowed us to test them as electrode-active materials for membranes in ion-selective electrodes (ISEs). © Pleiades Publishing, Inc., 2006.