The removal of organic contaminants, especially trimethylamine (TMA), have been successfully achieved using carbon activate. In this article, we report the formation of carbon activate (CA-SM) isolated from sub-bituminous coal in small mantles (SM) at the Mine “Mantos Negros” (Lebu, Chile). This coal was subjected to thermal oxidation with CO2 at 950 °C and their TMA adsorption capacity evaluated. SM and CA-SM were physically and chemically characterized showing that the activated carbon increased the surface porosity as well as the Iodine Index from 2.5 mg I2/g to 434 mg I2/g coal. The proximal and elementary analyses of CASM showed a significant reduction of sulfur, nitrogen and hydrogen, and increased composition of carbon and oxygen. These results together with FTIR and Boehm titration suggest that the surface composition of the activated carbon is acidic in nature. The adsorption of TMA by CA-SM was evaluated in dissolution at different pH and exposure time conditions. We found that TMA can be fully absorbed (50 ml TMA at 4 mg/L and 0.2000g of CA-SM) under neutral and basic pH after 60 minutes of exposure.