AbstractThe electron density distribution in deoxycytidine‐5′‐monophosphate (5′‐dCMP) molecule and dianion has been studied by the method of CNDO/2. The comparison between the results of calculation for the neutral molecule and the data obtained by Pearlman and Kim13 shows that there is a linear correlation between the atomic charges calculated using quantum chemistry and those derived from X‐ray results. However, partial charges for the deoxyribose fragment are correlated in a nonlinear manner. The influence of the protons added to the cytosine and phosphate residues on the atomic charges and bond orders of deoxy‐cytidine‐5′‐monophosphate has been analyzed here. The conclusion has been drawn that the semiempirical quantum‐chemical CNDO/2 technique is applicable to the mono‐nucleotide studies.