Surface roughness is well known to affect the initiation of boiling. Analysis of cavities on surfaces with a wide range of RMS roughness is carried out. Five aluminium surfaces, from polished (0.062 mu m) to very rough (12.53 mu m), are studied. The statistical cavity distribution obtained from 2D cross-sectional profile is discussed. The results obtained show that the cavity distribution on the surface is homogeneous. Moreover, small cavities enclosed in bigger cavities are observed to be the major independent nucleation sites. (C) 2009 Elsevier Ltd. All rights reserved.