In this work, we propose a hybrid adaptive control law for the half-bridge inverter subjected to the common problem of unknown load. This controller ensures the system robustness with respect to the output, taking into account the real nature of the signals, which means the continuous-time variables, (voltage and current signals) and the discrete-time variables, (switching signals). The adaptation is accomplished using a state observer and assuming that all states are measurable. Then, stability properties can be ensured using hybrid dynamical system theory and singular perturbation analysis. Finally, the proposed hybrid adaptive controller is validated in simulation. Index Terms-Half-bridge inverter, hybrid dynamical system, adaptive control, singular perturbation analysis.