A new Bi(III) complex, [C5H14N2](2)Bi(2)Br(10 center dot)4H(2)O, was preparedin aqueous solutionat room temperature. This complex crystallizes in the monoclinic space group P2(1) in with the crystal dataa=10.368(4), b = 14.012(7), c = 11.731(9) angstrom, beta = 99.20(4)degrees,V = 1682.4(17) angstrom(3) and Z = 2.Its atomic arrangement can be described by a three-dimensional structural networkbuilt of binuclear [Bi2Br10](4-) anions,uncoordinated 2-methyl piperazinium cations and water molecules. Different interactions connecting these entities are investigated by Hirshfeld surfacesanalysis. This compound,which stable up to 300 degrees C, absorbs at 355 nm and manifests a blue luminescence (at 442 and 480 nm) in the solid state. This compound exhibits an antioxidant activity in vitro. Four tests were donesuccessfully, 1,1-diphenyl-2-picrylhydrazyl (DPPH center dot), hydroxyl scavenging ability (OH center dot), ferric reducing power (FRP) and ferrous ion chelating (FIC) ability, using ascorbic acid as a control. (C) 2020 Elsevier B.V. All rights reserved.