In this study, a new perovskite solid solution system of La1−xNaxCrO3 (0 ≤ x ≤ 0.15) was synthesized by sol–gel method using citric acid as chelating agent. The samples were subjected to various calcination temperatures in order to investigate the physicochemical properties of the oxide affected by the parameter. Thermogravimetric analysis, Fourier transform infrared spectroscopy and X-ray diffraction (XRD) techniques are used to explore precursor decomposition and to establish adequate calcination temperature for the preparation of the nanopowders. A high crystallized La0.9Na0.1CrO3 with a orthorhombic structure was obtained when the precursor was calcined at 700 °C in air for 6 h. The studied compounds obtained after calcination at 700 °C were characterized by XRD, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy, powder size distribution and electrochemical measurements. The microstructure and morphology of the compounds show that the particles are nearly spherical in shape and are partially agglomerated. While the crystallite size decreases with increasing sodium content. The highest surface is achieved for La0.9Na0.1CrO3 oxide. The electrochemical measurements indicate that the catalytic activity is strongly influenced by sodium doping. The highest electrode performance is achieved with large sodium content.