The role of forest that serves as a mitigation for climate change often attract the attention of the international organizations toward the assessment on carbon sequestration potential that leads to future forest management. Baseline statistics on forest carbon stock is required to limit the deforestation and other forest degrading activities that aids in the reduction of carbon emission into the atmosphere. Therefore, a forest reserve in Kelantan, namely Gunung Basor was chosen to assess the carbon stock by measuring the above ground biomass. The objective of this study was to assess the relationship between altitude with aboveground biomass and carbon stock. The results obtained through this study is expected to act as a reference for future forest management. Above ground biomass and carbon stock at Gunung Basor were assessed in three altitude gradients namely low altitude (544-558m) middle altitude (816-900m) and high altitude (1010-1056m) using non-destructive sampling technique. Diameter at breast height and height of the trees were measured and relationship between the biomass and carbon stock with the altitudes was analysed through regression and correlation analysis. The maximum carbon stock was found in lowland dipterocarp forest with 223,123.13 kg per half hectare and minimum carbon stock was found at lower montane forest with 1,936.7 kg per half hectare. This indicates that carbon stock decreases with the altitude. The correlation analysis clearly highlights that the increase of the altitude decreases carbon content linearly (R² = 0.9999; r = -1, p < 0.01). Hence, Gunung Basor has the potential to serve as a carbon stock in future. Sustainable management and the awareness of public toward the importance of forest is required by apportioning productive and protective zones in Gunung Basor.