Ba doped CaO derived from waste shells of Turbonilla striatula are prepared by varying the amount of Ba between 0.5 to 1.5 wt% and used as heterogeneous catalyst in the transesterification of waste cooking oil (WCO). Catalyst characterization was done by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectrometer (FT-IR), thermogravimetric analysis (TGA)/differential scanning calorimetry (DSC) and Brunauer-Emmett-Teller (BET) surface area measurements. In the course of study it was observed that the catalytic activity was highly influenced by the basicity of the catalyst. The catalyst could be reused with slight drop in activity which was attributed to the loss of active sites and reduced basicity. The optimum reaction condition obtained for achieving maximum conversion > 98% were - 6: 1 methanol to oil molar ratio, 3 h of reaction time, 1.0 wt% catalyst amount and 65 degrees C reaction time. (C) 2014 Elsevier Ltd. All rights reserved.