Effect of crude glycerol addition to cattle dung on biogas generation and methane percentage was studied. Five percentages of crude glycerol were added to cattle dung during the anaerobic digestion process. The crude percentages ranged from 1 to 5% based on total solids (from 4 to 20 g). The experiments were conducted at mesophilic conditions of ambient temperature (27±2ºC) and 40 ºC. Twelve batch-digested units were used for laboratory experiments procedure. The digested units were divided to two groups with six digested units for everyone. The first group was operated at ambient temperature (27±2 ºC). While, the second group was operated at Forty degree centigrade. The full capacity of each digested unit was 5 Liters while, the working capacity was 4 Liters. The digester feeding consists of 3.2 L of cattle dung and 0.8 L of inoculum. Five digesters of every groups were fed with different percentages of crude (from 1 to 5%) namely G1, G2, G3, G4, and G5 in addition of G0 (control digester with 0 percentage of crude).The obtained results showed that the addition of crude glycerol to cattle dung during anaerobic digestion increased the biogas production rate and consequently the total biogas production at different temperature levels. Moreover, increasing the percentage of crude glycerol added increase the biogas production reached the maximum average biogas production rate of 0.212 and 0.296 L/L/day at G5 (5% crude glycerol added about 20 g) and different temperature levels of 27 ºC and 40 ^°C respectively as compared with G0 (0 crude glycerol added). The increasing ratios were; 13.60 and 17.89% at the same temperatures respectively. Moreover, the total biogas production reached the maximum values of; 51.489 and 59.279 L at the treatment of G5 and the same temperatures respectively, with increasing ratios of 14.27 and 18.08% at the same temperatures as compared with G0. The maximum value of methane content was 66% with increasing ratio of 8.28% and it was occurred at 5% crude glycerol and temperature of 40 ºC.