A new silver-chloroquine (CQ-Ag) complex [CQAgNO3, CQ = chloroquine, C18H26N3Cl] has been synthesized and characterized by using a combination of NMR (solution and solid-state), FTIR, molar conductivity and ESI/FT-ICR high resolution mass spectroscopy with DFT calculations. The CQ-Ag complex is formed by silver-CQ cations and nitrate counter anions, where the silver atoms are di-coordinated to chloroquines (CQ2Ag2+) through the quinoline sp2 N and diethylamino sp3 N nitrogen basic sites. These cations presumably form polymeric structures mainly as head-head catemers. The most important cationic fragments of the CQ-Ag complex, detected by ESI/FT-ICR, were CQAg +, CQ2Ag+, chloroquine singly (CQH+) and doubly protonated (CQH22+), whose formations are clearly favored by proton-displacement of the Ag+ cations. © 2913 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.