<p>Waste cooking oil can be effectively converted into biodiesel through thermal and electrochemical transesterification in the presence of heterogeneous Fe-Ca-based catalysts. However, the comparison analysis of these two processes on technological operation parameters and biodiesel thermal degradation characteristics was rarely studied, which was very important for industrial production and commercial application of biodiesel. In this work, we carried out the transesterification experiments via thermal and electrochemical processes using homemade magnetic Co/Fe-Ca-based catalysts, respectively. Both these two methods achieved fatty acid methyl ester (FAME) content of higher 80%. According to the comparison analysis of technological operation parameters, under the Co/Fe-Ca-based catalyst, electrochemical process had a less catalyst dosage, shorter reaction time, more mild temperature, and better water tolerance and acid resistance. The comparison analysis of biodiesel thermal degradation process and the thermal degradation reaction path prediction showed that biodiesel produced from electrochemical transesterification process had a higher unsaturated fatty acid methyl ester content, was easier to burn, and generated less CO₂. It was helpful in understanding the differences of biodiesel thermal degradation behaviors and its relationship with the properties and composition of biodiesel. It is hoped to provide a basic insight into thermal degradation of biodiesels through different transesterification methods as well as a good reference for improvement of technological process towards the specific quality of fuel.</p>