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Abstract. Swine manure (SM) and waste kitchen oil (WKO) are nutrient-enriched materials which are abundant in many parts of the world and need proper treatment to avoid potential pollution. Co-digestion of these organic substrates is interesting approach to balance their carbon to nitrogen contents and improve biogas production efficiency. In this study, ten 3.78-L (1-gallon) glass jars were set up to test potential of biogas produced from different loading ratios with working volumes at 1.38 L. Each jar was assigned to one of combinations between 2, 4 or 6 g-VS_SM/L/d and 0, 1 or 2 g-VS_WKO/L/d. The last jar was loaded with only 2 g-VS_SM/L/d and 3 g-VS_WKO/L/d to decide limit of oil loaded. Substrates were loaded every two days, and equal amount of digestates were replaced during each loading. Gas productions were compared with VS-destroy of feedstock to determine the effectiveness of digestion. Other factors, including Alkalinity, Ammonia and carbon dioxide concentrations, were recorded for assessment. Results showed that addition of WKO can significantly increase biogas produced from co-digestion in comparison with mono-digestion of manure when VS ratio of SM and WKO is less than or equal to 2:1. High amount of WKO can inhibit bacteria‘s activity and decrease gas produced and eventually stopped the digestion. Alkalinity and Ammonia concentrations depended correlatively on amount of VS_SM loaded. Three loading dosages (2 g-VS_SM/L/d and 1 g-VS_WKO/L/d, 4 g-VS_SM/L/d and 1 or 2 g-VS_WKO/L/d) yielded highest amount of biogas, at 1.06, 0.94 and 0.96 L/g-VS, respectively. These loading ratios and 2 g-VS_SM/L/d as the baseline are being replicated for further assessment of co-digestion. Due to COVID-19 pandemic, the test has been suspended since March 23, 2020 and will be restarted when University of Missouri opens again.