Bacillus mucilaginosus (B. mucilaginosus) and Thiobacillus ferrooxidans (T. ferrooxidans) have been earlier shown to be conducive to the demineralization of oil shale and thus improve shale oil yield. In this study, the combined effect of the two bacteria was investigated and was found to be greater than the independent effect of either organism separately. Due to the porosity generated by bioleaching, the Brunauer Emmett Teller (BET) surface area of bioleached oil shale increased to 31.2 m(2)g(-1) I. Aluminum retorting showed that the shale oil yield was increased to 13.18%, while approximately 15.38% extra shale oil was obtained, with a reduced loss of shale gas. Gas chromatography-mass spectrometry (GC-MS) results demonstrated that the additional shale oil was mainly low-and high molecular -weight hydrocarbons, due to the ability of shale oil to pass rapidly through the micropores without cracking. The obtained results indicated that the combined action of B. mucilaginosus and T. ferrooxidans during the leaching of oil shale contributed to the increased production of shale oil.