Vermicompost produced from oil palm empty fruit bunch (EFB) was analysed to examine its thermal degradation and morphological appearance. The thermal degradation of vermicompost produced from untreated EFB and EFB treated with oyster mushrooms was characterised via thermogravimetric analysis (TGA) and differential thermogravimetric analysis (DTGA). It was observed that vermicomposting accelerated the thermal degradation of EFB and minimized the lignin content, but reduced lignin degradation of raw EFB. However, the thermal degradation of lignin increased in treated EFB vermicompost. The structural characterization of EFB vermicomposting revealed that the surface of the treated EFB was more fragmented than the untreated EFB vermicompost and raw EFB.