Forest plays an important role on reducing the impact of global warming as carbon sink. Forest has an ability to absorb carbon on large scale and store it as biomass. This research was aim to determine the potential of aboveground biomass and carbon stock in pine-mahogany mixture stands in Specific Purpose Forest Area (SPFA) of Gunung Bromo. The systematic sampling with random start was used to determine the plot, and the distance between plots were 100 m. In total, there were 35 square plots, 20 × 20 m in size, that had been set up under the pine-mahogany mixture stands. This research was conducted by using non-destructive sampling method by measuring the tree volume. The pine-mahogany stands dominated by the trees with diameter class 20-30 cm. The tree density and stand volume were 431 trees/ha and 229.4 m3/ha. Estimated aboveground biomass, carbon stock, and CO2 equivalent in pine stands were 136.53 ton/ha, 64.17 ton C/ha, and 235.29 ton/ha, while for mahogany stands were 33.01 ton/ha, 15.56 ton C/ha, and 57.04 ton/ha, respectively. Thus, the total biomass and carbon stock in pine-mahogany mixture stands were 169.63 ton/ha and 79.73 ton C/ha. Meanwhile, total CO2-equivalent was 292.23 ton/ha.