A novel membrane dehumidifier is proposed for hybrid air conditioning system for which investigations are carried out for hot and humid climatic conditions. With separate cooling arrangements for air and desiccant, efficient control of both temperature and specific humidity is possible. In the present study, the effects of flow configurations, and operating parameters of air, cooling water and desiccant on the performance of the dehumidifier are investigated. The performance is presented in terms of moisture removal rate, and sensible, latent and total effectiveness. The configuration with cooling water flow in parallel and counter to air and desiccant respectively is found to be optimum for the dehumidifier. It is also found that the sensible effectiveness of the dehumidifier is independent of the changes in the operating parameters of desiccant. © 2019 Elsevier Ltd and IIR