The paper presents the results of simulations of a gaseous fuel supply system in a Wankel engine. The testing was conducted on a zero-dimensional model of the designed injection system that was fuelled by gaseous hydrogen into the intake manifold in the RX 50 Wankel engine. The Dymola software and its Pneumatics Module were used in the simulation. The experiments determined what phenomena would occur inside the injection system and helped develop a tool to optimize its design. The analysis dealt with the changes in the pressure and mass flow rate in the individual components of such a supply system. The research was done in steady states for one value of speed and load as the inlet system pressure.