The effect of average particle sizes (APS: 0.45 and 1.01 mm), solvent types (ST: distilled water, 2% citric acid solution, and 50% ethanol), and extraction times (ET: 40, 50, and 60 min) on the physicochemical properties, antioxidant capacity, and half maximal effective concentration (EC50) in calyces of Roselle (Hibiscus sabdariffa) was analyzed. The extracts obtained with distilled water and 2% citric acid solution had an intense red color which purities (C) were 78.5 ± 2.3 and 79.8 ± 2.2, respectively. The alcoholic extracts showed a dark red color (C = 75.9 ± 1.8). The alcoholic (820.2 ± 73.7 mg Trolox equivalents (TE)/100 g dry calyces) and acid extracts (773.34 ± 53.0 mg TE/100 g dry calyces) showed higher antioxidant capacity than the aqueous extracts (673.24 ± 116.0 mg TE/100 g dry calyces). The EC50 value was better for the alcoholic extracts, followed by the 2% citric acid extracts and finally by the aqueous extracts (13.4 ± 1.0, 14.9 ± 1.0, and 17.2 ± 1.2 mg of extract, respectively). According to results, the best antioxidant properties were achieved using an APS of 0.45 mm, 50:50% ethanol:water ratio, and ETs of 30 or 45 min.