Thok Reel is a Western Nilotic language of the Dinka-Nuer subgroup, spoken by a small tribe in southern Sudan. It is the only language within this subgroup for which there is virtually no linguistic information available, and it is my aim to fill this gap. I will present preliminary findings on the sound system of Thok Reel. These are based on data gathered during August-September 2009 in Juba, southern Sudan.