Lithium- and aluminum-containing niobates with the general formulas Ni4 − x Li x Nb2O9 − 1/2x and Ni4 − x Al2/3x Nb2O9 (x = 0.0025, 0.0125) have been synthesized, and their electrochemical properties have been investigated and compared to those of Ni4Nb2O9. Their electrical conductivity has been measured as a function of temperature. The results demonstrate that doping with lithium and aluminum oxides slightly increases the conductivity of the material. The main electrochemical characteristics of solid-contact thin-film electrodes based on the lithium-doped niobate have been studied: working pH range, linear range, slope and type of the electrode response, and response time of ion-selective electrodes. It is shown that not only Ni4Nb2O9 but also solid solutions based on this niobate can be used in ion-selective measurements.