Biodiesel is widely known as a renewable energy that can be directly used as an alternative diesel fuel. This paper emphasizes on the synthesis and characterization of lithium modified calcium oxide (CaO) derived from eggshell and cow bone waste materials. The synthesized catalysts were tested in term of their performance in biodiesel production from dairy waste scum oil (DWSO). The CaO was derived from eggshell and cow bone by calcination at 800 °C and then a mixture of CaO from eggshell and cowbone was combined with lithium via wet impregnation which resulted to four catalysts labeled as eggshell (ES), cow bone (CB), eggshell and cow bone (ESCB) and Lithium modified eggshell and cowbone (Li-ESCB). All catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer�Emmett�Teller (BET), Field Emission Scanning electron microscopy (FESEM) with energy dispersive X-ray (EDX) and Thermogravimetric Analysis (TGA) to interpret their morphologic, structural and chemical properties. The Li-ESCB showed better properties than ESCB, especially in BET analysis, where the surface area was 2.59 m2/g. Only in XRD analysis can it show the presence of lithium as it is very low in concentration (1 wt ), whereas EDX analysis cannot be detected. The biodiesel production were performed via microwave assisted transesterification and ES catalyst showed the highest biodiesel production (82). Even though Li-ESCB appeared as the best properties, the biodiesel was still low due to the inhibition of phosphorus from CB. The utilization of waste materials can contribute to sustainability development, environmentally friendly and cost-effective method. © The Author(s), under exclusive licence to Springer Nature Japan KK, part of Springer Nature 2024.