Proton conducting materials are used in electrochemical devices such as proton conducting fuel cells and proton conducting electrolyzers. These devices belong to the hydrogen energy field and serve the goals of clean energy and sustainable environmental development. Layered perovskites are a promising class of proton conducting electrolytes. Cationic co-doping is a well-known method to improve the transport properties of classical perovskite ABO(3). However, data on the application of this method to layered perovskites are limited. In this work, the bilayered perovskites BaLa1.9-xSrxGd0.1In2O7-0.5x have been prepared and studied for the first time. The possibility of oxygen-ionic and proton transport was demonstrated. Cationic co-doping was shown to increase the proton conductivity values by up to 1.5 orders of magnitude.