Efficient and profitable biomass combustion is often limited by ash related operational problems. Knowledge of the ash melting and sintering is of important, in terms of predict and reduce ash-related problems in biomass-fired boilers. In this study, chemical composition and melting behaviors of ashes from the four parts of P. sylvestris trees were investigated. The four parts from Pinus sylvestris trees are stem wood, bark, branch base and twigs. A simultaneous thermal analyzer (STA) was used to characterize the melting behavior of selected biomass fuels in oxidizing atmosphere. Ash melting process was identified as the distinctive endothermic peaks on recorded DSC curves. The results showed that the stem wood of pine contains higher contents of most of the ash forming matters than other tree parts. Chemical composition of ashes from four parts of the pine tree is dominated by element Ca, K, Mg, Mn, P and Si. The K, Na and P contents in the twigs are significantly higher than that of stem wood, bark, and branch base indicating high tendency of ash melting and slagging. STA experiments indicated that the melting process of the studied fuel ashes start in the temperature range of 930-965 °C. Scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometry (EDX). Analyses results showed that the stem wood ash remains loose structure even after 1000 °C sintering treatment. But the ashes originated from top branch show sign of sintering at 1000 °C. The obtained results of present work can be considered as useful information within an industry interest for a prediction of the forest biomass ash melting behavior.