Á preventive fuels pre-treatment technique, based on low temperature carbonization, has been applied for the production of clean coals from two poor quality Greek coals and an Australian coal sample. A lab-scale fixed bed reactor and a TA SDT Q600 thermogravimetric analyser were used for the production and reactivity characterisation of the clean coals. Special attention was paid to the removal of pollutants such as S, N, Hg and Cl. To account for possible mineral matter effects, mainly on sulphur removal, tests were also performed with demineralized coal. Results showed that the low temperature carbonization technique might contribute to clean coal production by effectively removing the major part of the existing polluting compounds contained in coal. Therefore, depending on coal type, nitrogen, mercury and chlorine abatement continuously increases with temperature, while sulphur removal seems to reach a plateau above 500-600°C. Moreover, the prolongation of carbonization time above 20 minutes does not affect the elemental conversion of the pollutants and carbonization at 500 - 600°C for ~20 minutes may be considered sufficient for clean coal production from poor quality coals. Clean coal production at higher pyrolysis temperatures results in observed higher initial combustion temperature, mainly due to lower volatile content in produced chars.