The complex formed from the reaction of an important thione based stabilizer in conventional silver halide photography, methyl- 2-mercaptobenzimidazole (MBI), and silver bromide has been isolated for the first time as a single crystal and characterized by X-ray structure techniques. The resulting compound is tetrameric and has the formulation [AgBr·MBI]₄ and also contains residual solvent from the crystallization process. The crystal and molecular structure of [AgBr·MBI]₄ consists of intertwined dimers of [AgBr]₂ four-membered rings that connect the foundational silver-ercaptobenzimidazole [AgS]₄ eight-membered rings into a high molecular weight polymeric network superstructure. The complex demonstrates the powerful silver halide solubilization properties of the thiourea type ligand. The bridging sulfur remains in the thione form and N-H…Br-Ag hydrogen bonds suggest the title complex is an intermediate in the formation of the deprotonated AgMBI complex. Normal Ag-Br and Ag-S bond lengths were found: Ag-S = 2.5026(8), Ag-Br = 2.7423(9) and 2.7956(10) Å, C_9.50H₁₁AgBrN₂O_0.50S, Cell Data: I4₁/amd, a = 19.1034(2) Å, b = 19.1034(2) Å, c = 13.5019(2) Å.