A conditioning dehumidifier system is a simple technology to improve air quality and also reduces air conditioning costs. This experimental study evaluated the performance of a liquid desiccant system by adding copper oxide nanoparticles (NPs). The effect of operating parameters, such as inlet air humidity ratio and desiccant flow rate on air dehumidification rate, was also investigated. The desiccant solution contained 48 wt.% CaCl2 and 0.35 vol.% of CuO NPs. Comparison of liquid desiccants demonstrated a mean difference of 4.5 g/s ⋅m2 in the air dehumidification rate by solutions with and without CuO NPs.