Cardiocyclide, a new Russian class III antiarrhythmic agent, was developed at the State V. V. Zakusov Science Research Institute Pharmacol., Russian Academy of Medical Sciences.The aims of the present work were to study the physicochem. properties of the hydrochloride salt of this agent (N1-(3-diethylaminopropyl)-N1-(p-nitrobenzoyl)aminoacetic acid N,N-dicyclohexylamide HCl) and to develop an anal. method for this compoundIR, 1H NMR, and UV spectra were obtained for cardiocyclide; its solubility was studied; its melting temperature, weight loss on drying and the transparency, color, and pH of its solutions were determinedThe purity of material containing compound I was determined by thin-layer chromatog.; quant. cardiocyclide contents were estimated by non-aqueous titration