Biodegradable plastics have been introduced to the market to substitute petro-based plastics to alleviate plastic pollution. Biochemical methane potential tests were carried out on food wastes (FW), with or without pre-treatment, compostable bag and a mixture of food waste and compostable bag (CB) to examine the anaerobic biodegradability of those materials. Anaerobic tests were carried out in mesophilic (35oC) conditions. The aim of this work is to study the residuality of compostable bags in anaerobic digestion. At the end of the process, a dry mass of 26 % and 28 % was recorded for compostable bag and co-digestion of compostable bag and food waste respectively. The CB added to the feed did not have a negative effect on reactor performance, but seemed to have higher biogas production. Moreover, co-digestion with CB improved biogas production by 0.8-1 times. The best VS removal efficiency of approximately 68% was achieved for FW & CB substrate. Therefore, when the compostable bag was used as a combination of substrate with food residues it produced larger amounts of biogas than samples containing only food residues. This result highlights the fact that the compostable bag does not adversely affect the process.