In this study, coal samples were collected from 17 various locations in Turkey. Collected and cleaned samples were tested in terms of ash and volatile matter content, and ash chemical composition. Coal utilisation includes coal cleaning, coal size reduction (crushing grinding), and finally coal combustion. As regards to coal combustion (ash fusion, slagging fouling), ash chemical composition is mostly addressed, while as regards to coal grindability however, effect of ash chemical composition is rarely considered. Although some studies have included ash chemical composition in terms of coal grindability, no research have focused grinding index as similar to slagging index. In this study, coal grindability was addressed and alkalinity and acidity of 17 coal sample was related to their hardgrove grindability index (HGI) values. A new term of coal alkalinity and acidity has been introduced and a new prediction method of coal grindability (grinding index) based on these abovementioned parameters was proposed.