the effect of polycarboxylate superplasticizer on thermal stability and the kinetic thermal decomposition of oPc without and with 1.0 and 1.5% wt% plasticizer has been studied at temperature range of 30-1000 oc. the study was done by means of thermogravimetry (tG) technique under non-isothermal condition at a heating rate of 10 k/min. the results showed that the decomposition occurs for the superplasticized and neat oPc paste in three steps. the neat oPc was found to decompose at higher temperatures than those for the superplasticized paste. the kinetic parameters for each one of the decomposition steps were calculated through four calculation methods and the kinetic mechanisms were determined from the thermal data analysis using 35 solid state reaction models. the results showed that the mechanisms of decomposition steps depend on the percentage of the superplasticizer added to the paste. the thermodynamic parameters ΔS#, Δh# and ΔG# were also computed and discussed.