A molding tool for producing a component in a gas-assisted injection molding process includes a mold cavity, and an injection device with a pressurized gas source. The pressurized gas is fed into the plastic melt introduced into the mold cavity. The plastic melt is pressed against the inner walls of the mold cavity. The injection device has a piston with an injector head and moveably guided in a passage of a molding tool connected with the mold cavity. The injector head forms a part of the inner walls of the mold cavity in an idle position of the piston, and is pressed into the plastic melt as the piston moves to its operating position, so that the pressurized gas flows through the passage into the plastic melt in the mold cavity. The piston is moveable by the gas fed through the passage into the plastic melt.