Treatment of ruthenium carbonyl, [Ru 3 (CO) 12 ] with phenylseleno tribromide PhSeBr 3 afforded a new triruthenium cluster, [(CO) 10 Br 4 Ru 3 (μ-SePh) 2 ] (1). Its molecular structure was determined by single crystal XRD method (P2 1 /c; a = 10.514(3) Å; b = 10.814(3) Å; c = 19.063(5) Å; β = 105.064(4)°; V = 2093.1(10) Å 3 ) and shown to have two lateral Ru(CO) 3 Br 2 units attached via two PhSe bridges to a Ru(CO) 4 center forming a chain-like Ru–Se–Ru–Se–Ru cluster core. This is in contrast with a recently reported reaction of PhTeBr 3 with [Ru 3 (CO) 12 ] which formed a monomeric complex of ruthenium-dicarbonyl-dibromo fragment coordinating two PhTeBr ligands, [(CO) 2 RuBr 2 (PhTeBr) 2 ].