Procceedings of: 3th Conference on renewables for desert regions. Global Conference on Renewable energy and Energy Efficiency for Desert Regions 2011 "GCREEDER 2011". Tokk place 2011 April 26-28,in Aman (Jordanian). The Event Web site is http://www.solarthermalworld.org/content/gcreeder-2011-amanThe thermal decomposition of biomass (pine pellets) and sewage sludge was studied using thermogravimetric analysis under an inert atmosphere and the Distributed Activation Energy Model (DAEM) was employed. The activation energy and the frequency factor that characterize the kinetics were determined for both samples. A simplification of the process for prediction of devolatilization curves was proposed, evaluating its validity for both cases. The simplified method was found to combine both simplicity and low deviations with experimental data.This work has been partially supported by the National Energy Program of the Spanish Department of Science and Education (ENE2006-01401), the Spanish Government (DPI2009-10518 MICINN) and the Madrid Community (CCG07-uc3 m/amb-3412, CCG08-uc3 m/amb-4227 and P2009/ENE- 1660).Publicad