This paper presents an experimental study on mechanical and thermal properties of concrete made from oil shale ash, cement and sand and/or aggregate mixtures. The properties determined were compressive strength and thermal conductivity of the concrete mixtures. The used ash was obtained by direct combustion of Sultani oil shale. The composition of ash is close to that of Estonian oil shale ash. Thirty-two cubes and twelve cylindrical samples were prepared to conduct compression and thermal conductivity tests, respectively. The cure duration for the cubes was 1, 7, 14, and 28 days, for the cylinders - 28 days. The content of ash in binder was 10, 20, and 30% for compression and 10, 20, 30, 60, and 70% for thermal tests. The weight ratios of cement: aggregate, cement:sand and water:binder were 1:4.5, 1:3 and 1:2.5, respectively, kept constant for each sample. The results are compared with the corresponding data for concrete made without oil shale ash. The results show that compressive strength decreases with increasing proportion of ash in the mixtures and increases with increasing curing time for all cases. Thermal conductivity of concrete samples decreases with increasing content of ash in the mixtures.