In this study, the thermal behavior of two olive mill wastes samples such as olive mill solid waste (OMSW) and concentrated olive mill wastewater (COMWW) was examined at different heating rates ranging from 5 to 50 K/min in inert atmosphere using the technique of thermo gravimetric analysis. Avrami theory and iso-conversional Starink approach were used in this work to evaluate the kinetic parameters, including apparent activation energy (Ea) and reaction order (n). For the range of conversion degree investigated (20-80%), the values of apparent activation energy for olive mill solid waste (OMSW) were 147.51-158.79 KJ/mol and 200.13-212.51 KJ/mol for hemicellulose and cellulose respectively. Whilst the apparent activation energy of concentrated olive mill wastewater (COMWW) varied from 128.41 to 138.85 KJ/mol and from 201.3 to 226.67 KJ/mol for hemicellulose and cellulose respectively. With varied temperature (515-753 K), the corresponding values of reaction order was increased from 0.1004 and 0.1061 to 0.1787 and 0.2886, along with a decrease to 0.1220 and 0.1889 for OMSW and COMWW respectively.