This paper proposes a passivity-based controller for a single-phase PWM current-source inverter feeding a resistive load. The controller design is based on the dynamic model of the inverter and the energy shaping plus damping injection idea of the passivity-based approach for a known resistive load case. It is shown that the unknown load resistance can be estimated by an adaptive estimation algorithm. However, since the inductance value ( L ) is directly proportional to the estimation accuracy and is inversely proportional to the dynamic response of the proposed controller, it should be chosen to make a compromise between dynamic response and correct reference estimation for the inductor current. Computer simulations and experiments are presented to show the feasibility and the performance of the proposed control strategy.