Adsorption and desorption properties of desiccants are of key significances to the dehumidification performance of a compact dehumidification component named desiccant coated heat exchanger. This work developed novel activated carbon (AC) - sodium polyacrylate (PAAS) composite coated aluminum sheets with high adsorption property and good desorption ability. Adsorption and desorption properties of AC-PAAS coated aluminum sheets were investigated under different air conditions. Cyclic adsorption-desorption features with internal-cooling/heating were conducted. Results showed that composite coated aluminum sheets had nearly 2∼3 times higher water uptake than an AC coated sample in the range of medium- to high-relative humidity (60%∼90% RH). More than 95% of adsorbed water in composite samples was released at 70 °C & 20% RH, and 86% was still desorbed when the air temperature was decreased to 40 °C. Adsorption capacities and rate coefficients of composite samples with internal-cooling could be 2.3 and 1.5 times higher than those without. This paper provides a way to develop composite desiccants with high cyclic water uptake performance in the fields of adsorption cooling, solid desiccant air-conditioning and atmospheric water harvesting. •Activated carbon-sodium polyacrylate coated aluminum sheets are prepared.•Adsorption capacity of a composite had nearly 2–3 times of pure activated carbon.•Composite can be well regenerated at the air of 40–70 °C.•Adsorption capacity of composite can be 2.3 times higher if internal-cooling applied.