In this study, cellulose sulfoacetate (CSA) was produced with cellulose extracted from sugarcane bagasse with sulfuric acid as a catalyst under homogenous conditions so that the derivative could be applied as an additive for mortar of Portland (Cimento Portland de alta resistencia inicial, CPV-ARI) cement. The IR spectra showed that only precipitate C presented the characteristic band of sulfate groups (807 cm(-1)) and was, therefore, the sulfoacetylated derivative. CSA presented a degree of acetylation of 2.70 and a degree of sulfonation of 0.063, and the presence of sulfate groups in the derivative displaced the position of C(6) to a lower field in the C-13-NMR spectrum and influenced reduced viscosity as a function of concentration. The evaluation of CSA as an additive showed that for a polymer/cement ratio of 0.6%, an increase of 13.80% was achieved consistently, and an increase of 21.05% in the potential tensile of adhesion strength was also achieved. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012