Frost formation on the air side of an air-refrigerant heat exchanger operating under low temperature conditions results in an increase in thermal resistance and an increase in pressure drop. We have focused on the removal of water vapor in the air causing frost layer by adsorbent. In this study, an adsorbent-coated fin-and-tube heat exchanger under a continuous frosting-condition such as the outdoor unit of air-conditioner has been evaluated experimentally. The effect of inlet air velocity on heat transfer characteristics and mass transfer characteristics with frost formation of the test heat exchanger was investigated. The result showed that the frost layer thickness of the test fin surface was zero for about 10 minutes after the start of the experiment in the case of 1.0 m/s. It was found that the adsorbent has an effect on the frost formation suppression.