The present study applies the experimental and numerical inverse methods to determine the average heat transfer coefficient (h) over bar and heat transfer coefficient under the isothermal situation (h) over bar (iso) on a vertical square fin of the two-row plate finned-tube heat exchangers with four circular tubes for the staggered arrangement and various air velocities and fin spacings. These tubes may not have the same temperature. The experimental fin temperature measurements, ambient air temperature and air velocity are obtained from the present small wind tunnel. Due to the non-uniform distribution of the heat transfer coefficient, the square plate fin is divided into several sub-fin regions before performing the inverse scheme, and the average heat transfer coefficient in each sub-fin region is assumed to be unknown. The results show that the (h) over bar and (h) over bar iso values increase with the air velocity and fin spacing for the staggered arrangement. In order to validate the reliability of the present results, the (h) over bar (iso) value is compared with the existing correlations for the staggered arrangement. (C) 2012 Elsevier Ltd. All rights reserved.