In this study trace element and radioactive element contents of the Hatildag oil shale (HOS) in Turkey and geochemical processes controlling the deposition of these elements are investigated. Ratios of redox-sensitive elements show that HOS were formed in mostly dioxic-anoxic and partly euxinic conditions. Element contents of shales in the northern part are associated mostly with clays and slightly with organic material. It was determined that uranium in southern part is derived from phosphates and calcium-carbonates and thorium is mostly originated from organic material and slightly associated with phosphate and calcium-carbonate. Radioactivity of HOS is derived from uranium and potassium. (C) 2016 Elsevier Ltd. All rights reserved.