The guava seed (SEGUVE) was characterized by ultimate and proximate analysis. In SEGUVE the principal thermal effect occurred at 363 degrees C and this can be attributed to the cellulose degradation, which was the main component (similar to 61%). The guava seed has an acidic character with a high content of bulk functional groups (C=O) and these characteristics were affected by carbonization. Two samples of carbon were prepared from the seeds at 600 and 1000 degrees C without chemical activation. Adsorption of eight acid dyes belonging to the monoazo and anthraquinone class was studied at 25 degrees C. The non-carbonized SEGUVE adsorbed the acid dyes more efficiently than SEGUVE-C600 and SEGUVE-C1000 although the specific surface of the raw material SEGUVE was low. (C) 2008 Published by Elsevier Ltd.