The optical and ESR spectra have been examined for complexes of Cu(I) with various radicals, which contain various numbers of Cl ions in the central-atom coordination sphere. The spin-Kamiltonian parameters have been determined for all these radical complexes, and the observed ESR spectra have been compared with those calculated with allowance for second-order effects. The observed values for the isotropic and anisotropic components of the HFI constant from the central ion have been used to estimate the contributions from the 4s and 3d2z orbitals of the copper ion to the unpaired-electron MO. Quantum-chemical calculations have been performed by the INDO method on the electronic structures and geometries of complexes formed by CH2OH with Cu(I) for various Cl contents in the coordination sphere. The radical is coordinated by the p orbital on the carbon atom, and the stabilities of the radical complexes decrease as the number of Cl ions in the coordination sphere increases. A geometry close to planar is proposed for the CuCl4-3 fragment in a complex containing four Cl ions.