This study investigates the effect of fin pitches and fin materials on the air-side performance of crimped fin-and-tube heat exchangers in the range of high Reynolds numbers (4000-13000). The test samples are made from copper and aluminium with different fin pitches (f(p) = 3.2, 4.2 and 6.2 mm). It is found that the proposed simple average effectiveness equation from the pure counter and parallel circuitry arrangement can well represent the effectiveness-NTU relationship for the current z-shape arrangement. The experimental results reveal that the fin pitch casts insignificant effect on the heat transfer characteristics (Colburn j factor). However, a detectable rise of the friction factor is seen when the fin pitch is increased to f(p) = 6.2 mm. On the other hand, the effect of fin material on the airside performance is negligible. (C) 2010 Elsevier Ltd. All rights reserved.