AIMCM-41 molecular sieves were synthesized starting from a hydrogel with the following molar composition-4.58 SiO2:0.0485 Na2O:1 CTMABr:0.038 Al2O3:200 H2O. Cethyltrimethylammonium bromide (CTMABr) was used as structure template. The obtained materials were characterized by XRD, FT-IR and TG/DTG. The model-free kinetic algorithms were applied in order to determinate conversion, isoconversion and apparent activation energy to decomposition of the CTMA+ species from the AIMCM-41 materials. (C) 2003 Elsevier B.V. All rights reserved.