The production of hydorgen sulfide from liquid swine manure is influenced by the manure settling characteristics and the initial sulfate concentration was studied in the laboratory. The manure was settled in a 30cm diameter x 120cm high column for 24 hours and then divided into three layers based on solids content. The manure from different layers was placed in separate closed jars and stored for 30 days a 22 degrees Cesius. The total sulfide, total solids, volatile solidds, pH in the manure, and hydrogen sulfide in the effluent gas stream was measured. The sulfide production rate was highest for all three manure layers during the first 5-10 days of storage. The top manure layer had the lowest solids content and the highest sulfide concentration. Howwever, due to the l;ower pH levels in the bottom layer, the concentrationof molecular H2S is higher in the bottom layer than the top layer. Mathematical equations for predicting H2S concentration and production rates in the different manure layers were derived. Three levels of initial sulfate concentration were used to test the effect of initial sulfate concentration in the liquid swine manure on sulfide production. Higher sulfate concentration in the manure resulted in higher sulfide concentration during the storage priod. From the observations made, it was confirmed that reducing the sulfate concentration in the water supply would help reduce the sulfide production in the pit.