Particles of the copper(I) thiosemicarbazone complex [Cu(Brcatsc)(PPh3)2Cl]·CH3CN ( 1 ), Brcatsc = 2-bromo-3-phenylpropenalthiosemicarbazone, were synthesized by an ultrasonic-bath-assisted method and characterized by elemental analyses, NMR ( 1 H, 13 C, and 31 P) and FT-IR spectroscopies, X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The thermal stability of 1 was studied by thermal gravimetry analysis and its structure was determined by single crystal X-ray diffraction. The compound 1 is a mononuclear complex with the copper(I) ion coordinated in a distorted tetrahedral geometry by one S atom of Brcatsc, two P atoms of two PPh 3 , and one Cl atom. The complex involves the Brcatsc thiosemicarbazone ligand in an S monodentate bonding mode. The antibacterial activity of the ligand and its copper(I) complex was studied against two gram-positive ( Staphylococcus aureus and Enterococcus faecalis ) and two gram-negative ( Escherichia coli and Pseudomonas aeruginosa ) bacteria.