Inserting a phase change material (PCM) directly into an adsorbent is proposed, for the first time, as a novel method for recovering the generated heat of adsorption. In the PCM-inserted adsorbent, adsorption and recovery of the heat of adsorption can occur simultaneously. As a conceptual model, PCM-inserted mesoporous silica SBA-15 was experimentally prepared, and a dehumidifying fixed-bed adsorption process was simulated on the basis of the experimental data. The simulation was run for a theoretical investigation under adiabatic conditions over five types of adsorbents with/without PCM. The PCM-inserted SBA-15 showed isothermal behavior in a first few minutes owing to the heat recovery effect of the PCM, demonstrating the highest performance.