A huge quantity of crop residues and animal dung as organic matter is produced in Pakistan and is a potential substrate for producing renewable energy in the form of methane. It is well established that nanoparticles are nutrient's source for the microorganism. The present study evaluated the effect of magnetite nanoparticles (Fe3O4 NPs) on co-digestion of canola straw with buffalo dung (CS: BD) and banana waste plant with buffalo dung (BPW: BD). Before adding the dosage of Fe3O4, the nanoparticles (NPs) was synthesized and characterized. Five different dosages (0.4, 0.5, 0.81, 1.22, and 1.63) mg were implemented in two ratios of CS: BD (40:60) and BPW: BD (60:40), based on 5 g of volatile solids (VS). The experimental results showed that all doses effective stimulated microbial activities in the co-digestion and enhanced methane production. Maximum methane yield of 256.0 mLCH(4)/gVS and 202.3 mLCH(4)/gVS was obtained at a dosage of 0.81 mg and 0.5 mg for CS and BPW respectively compared with control. Additionally, cumulative methane yields were statistically analyzed (p < 0.05). However, compared with the optimized dose of Fe3O4, CS produces the higher volume of CH4 than to BPW due to oilseed crop and carbon content. (C) 2018 Elsevier Ltd. All rights reserved.