The homogeneous catalytic systems for olefins carbonylation under mild conditions have been developed. The systems consist of palladium compounds, stabilizing ligands, and some promotors. The main advantages of these systems are high catalytic activity and selectivity as well as low corrosive attack. Ethylene carbonylation into propionic acid is carried out at 90-150 oC and 7-50 atm. with selectivity 97-99 % and activity as high as 1500 turnovers per hour. The data obtained allow to expect that the technology will be resources- and energy-efficient, and ecologically safe.