The use of pozzolan in cement provides economic advantages and improves the physico-mechanical properties of cement. Fly ash and blast furnace slag are widely used in cement as pozzolanic materials. In this study, obsidian known as volcanic glass which crops out in the lkizdere (Rize) region of NE Turkey was investigated as a pozzolana in cement. Mainly the pozzolanic activity, chemical and physico-mechanical properties of the obsidian cement were compared to the properties of the fly ash and blast furnace slag cement. According to laboratory test results, obsidian was seen to provide more positive effects compared to the properties of fly ash cement. It was concluded that obsidian was equivalent to blast furnace slag as a pozzolan. As a result, the obsidian located in the lkizdere region could be used as a pozzolana in cement. (C) 2017 Elsevier Ltd. All rights reserved.