Unidentified Clinker causes a loss of reserve in mine activity. Clinker is created by in situ coal heating and has certain quality characteristics. This research investigated the effect of coal quality on clinker deformation. This research is located in the Latih Formation, Binungan Area, Berau Regency, East Kalimantan Province, Indonesia. Coal quality samples were derived from 77 drillholes, consisting of 10 seams with a thickness > 2.25 m and distributed laterally and vertically. Coal quality parameters consist of Inherent Moisture (IM), Ash Content (AC), Volatile Matter (VM), and Fixed Carbon (FC). The coal quality sample is classified into the clinker seam group and the non-clinker seam group. Each quality parameter is compared with seam thickness in a scatter graph. The result of this study is that coal that has the potential to deform into clinker has a value of IM < 14.49 %, VM > 39.8%, and FC > 42.08 %, but AC is 3.63% relatively stable, or there is no correlation to clinker deformation. Among these four quality parameters, moisture significantly differs between seam clinker and non-clinker. This study concludes that the lower layer of coal or older seam in the Binungan area has a higher potential to be clinker, which is caused by increased FC and VM values and a decrease in IM value.