Susilowati T, Kawiji, Ariviani S. 2012. Antioxidant capacity and curcuminoid content of temulawak rhizome extract (Curcuma xanthorrhiza) using water solvent with variation of solvent proportion and heating method. Biofarmasi 14: 83-89. Temulawak (Curcuma xanthorrhiza Roxb) rhizome has some advantages such as analgesic, antibacterial, antifungal, antidiabetic, and antioxidant agent. The advantages of Temulawak due to its curcuminoid, germacrene, xanthorrhizol, alpha-beta-curcumin contents. Antioxidant capacity of temulawak rhizome is dominated by phenolic compounds including curcuminoid. Although, curcuminoid doesnâ€™t soluble in water, commonly the consumption of temulawak rhizome extract was done by water solvent extraction, such as in herbal medicine and health drinks. In the other way, Curcuminoid tends to decrease during heating process in boiling water because of its degraded to be ferulic acid and diferuloylmethane, so it is necessary to study the heating method which is suitable to minimize the damage of curcuminoid and decrease of antioxidant capacity. The research used Completely Randomized Design (CRD), which consists of two steps. The first step was to determine the effects of solvent proportion, includes five levels (1:1, 1:2, 1:3: 1:4, 1:5). The second step was to determine the effects of heating method on the three selected samples which include three levels: 100Â°C for 5 minutes, 80Â°C for 15 minutes, and 65Â°C for 30 minutes. Curcuminoid content of temulawak rhizome extract increased along the solvent increasing proportion, the optimum solvent proportion of 1:4. Total phenolic content and antioxidant potency of extracts of Temulawak rhizomes decreased along the increasing of proportion of the solvent. The long time of heating method although using low temperature determined the decreased of content of curcuminoid, the total phenolic content and antioxidant potency. Extraction techniques and the best heating of antioxidant capacity used Temulawak solvent proportion of 1:1 and heated at 100oC for 5.