Context. BaTiO3 is one of the most important ferroelectric oxides in the electronic applications. Also, it has attractive properties for catalysis that could be used for reducing the contamination levels especially carbon monoxide, CO. CO is one of the main gaseous pollutants generally released from the combustion of fossil fuel. In this work, the catalytic properties of pristine and Au-modified BaTiO3 perovskite for CO hydrogenation are studied. The CO adsorption and hydrogenation on pristine BaTiO3 leads to formaldehyde synthesis as the most stable product through two possible routes. Further hydrogenation stages are less probable. On Au-modified BaTiO3 formaldehyde is the principal product too but Au adatom induces selectivity making just one reaction route as the most stable. After BaTiO3 modification with Au unpaired electrons were generated. These unpaired electrons increased the adatom reactivity. According to the obtained results, pristine and Au-modified BaTiO3 can adsorb and hydrogenate CO generating formaldehyde as the principal product. BaTiO3 modifications with Au increases the reactivity and selectivity of the perovskite in the CO hydrogenation reactions. Methods. The study was performed through ab initio calculations using the periodic Density Functional Theory (DFT) as implemented in Quantum ESPRESSO. DFT calculations were carried out using the Plane Wave self-consistent field (PWscf). Spin density was considered for systems with unpaired electrons. Plane wave basis set was used to represent the electron states. Vanderbilt pseudopotentials with nonlinear core correction were used to model the interaction of ionic cores and valence electrons. Exchange-correlation energies were treated within the generalized gradient approximation (GGA) with the Perdew-Burke-Ernzerhof (PBE) parameterization.