Five basic geometries (cylinder, cube, diamond, pyramid and hemisphere) are comparatively examined at a Reynolds number of 1.7 x 10(4) to determine the effect of a single roughness element on surface heat (mass) transfer. Local mass transfer measurements obtained using the naphthalene sublimation technique are substantiated by Bow visualization. Results show that the upstream horseshoe vortex system and the inverted arch-shaped vortex immediately behind the elements are the dominating effects in element-endwall interaction. Based on information concerning the extent of spanwise influence of each element, an inter-element spacing may be proposed for array configurations to achieve optimal heat transfer performance.