The decomposition of basic nickel carbonate in the presence and absence of NaNO3 sodium nitrate)-KNO3 (potassium nitrate) eutectic melt has been studied by employing isothermal TG and dynamic TG-DSC techniques. The rate constants for the decomposition in the presence of eutectic melt were found to be higher than when carbonate alone was heated. In both cases, nickel oxide was found to be the end product. Catalytic activities of nickel oxide obtained by the two methods were tested for their efficiency in decomposition of polystyrene (PS). It was found that at higher temperature (330 and 360 degreesC), the nickel oxide obtained from eutectic melt was more active than that obtained by direct decomposition.