This paper presents a review of data reduction method for heat and mass transfer characteristics of fin-and-tube heat exchangers with dehumidification. There are many reduction methods for fin-and-tube heat exchangers under dehumidifying conditions. The data reduction methods being reviewed includes the original Threlkeld method, direct method, the equivalent dry-bulb method. tube by tube method, the fully wet and fully dry tiny circular fin method, and the finite circular fin method. Among these methods, the original Threlkeld method, direct method, the equivalent dry-bulb method are lumped method while others can divide the fin-and-tube heat exchangers into small segments for more accuracy in handling the surfaces to be fully dry, fully wet, or partially wet. In addition, the mass transfer characteristics can be obtained from the modified process line equation incorporated with the preceding methods. It should be noted that the conventional assumption of constant ratio (h(c,o)/h(d,o)C(p,a) approximate to constant) is actually incorrect. This present paper can be used as the first guideline for the researcher for reducing the experimental data for fin-and-tube heat exchangers under dehumidifying conditions. (C) 2008 Elsevier Ltd. All rights reserved.