A purified beta-xylanase (Xyn III) from Humicola grisea var. thermoidea was used for studies of atomic force microscopy (AFM) in order to investigate its interaction with oxygen-bleached kraft pulp. The results of AFM indicated that Xyn III caused significant changes in the topography, texture and elasticity of kraft pulp. It was observed a reduction in mean of RA (parameter associated to sample roughness), RMS (roughness mean surface parameter), average height, maximum amplitude of topography and texture, and roughness in Xyn III-treated kraft pulps. RMS parameter analysis showed higher amplitude of elasticity for the Xyn III-treated kraft pulp. For the same pulp sample was observed an increase in the kurtosis surface parameter, while the indexes of texture direction and fluid retention parameter were reduced when compared to the control. (c) 2006 Elsevier Inc. All rights reserved.