The effect of temporal variation in chemical composition on methane yields of rendering plant wastewater was studied in batch experiments at 37 °C. In total, 14 grab samples were collected from Monday through Friday (Day 1 to 5) from a rendering plant located in Queensland, Australia. Each day, three samples were collected: early morning (S1), midday (S2) and afternoon (S3). Chemical analyses showed that a significant different in total solids (TS), volatile solids (VS), and chemical oxygen demand (COD) was noticed among the samples. TS content ranged from 0.13% to 1.82% w/w, while VS content was between 0.11% and 1.44% w/w. Among the samples, S2 of Day 3 had the highest COD concentration (10.5 g/L) whilst S1 of Day 1 had the lowest COD (3.75 g/L) and total volatile fatty acid (VFA) concentration (149.1 mg/L). In all samples, acetic acid was the dominant VFA and accounted for more than 65–90% of total VFAs. Biochemical methane potential studies showed that the highest methane yield of 270.2 L CH4/kgCODadded was obtained from S3 of Day 3. Whilst the lowest methane yield was noticed for S1 of Day 1 (83.7 L CH4/kgCODadded). Results from kinetic modelling showed the modified Grompetz model was best fit than the first order model and a large variation was noticed between the experimental and the modelled data. Time delay ranged from 2.51 to 3.84 d whilst hydrolysis constant values were close to 0.21 d−1. Thus, the study showed that chemical composition of incoming feed to a biogas plant varies throughout the week and is dependent on the chemical composition of organic materials received and the amount of steam used for rendering process.