The new Cu-Ca heteronuclear complex has been obtained by the method previously reported [1]. The structural composition of the blue colored crystals is still under investigation, however based on the obtained IR and elemental analysis data the complex has the composition [CuCa(SalH)4(DMAA)4(H2O)].  In EPR measurements, the single crystal with sizes (3.9 x 1.7 x 1.1) mm3 was used. For determining the main values of g- and a-tensors the selected single crystal was rotated in three planes XOY, YOZ and ZOX. Depending on the orientation of principal axes of the crystal with respect to the magnetic field, the EPR spectrum has changed from a single resonance line (Fig. 1) to a four component spectrum due to the hyperfine interaction between unpaired 3d-electron of Cu2+ ion and copper nucleus with the spin I = 3/2 (Fig. 2). The Cu2+ ions are part of the crystalline cell. For revealing the hyperfine structure in this case, a sufficiently large distance is necessary between Cu2+ ions. Consequently, a spectral resolution of the hyperfine structure was detected. This is possible because there exist Cu2+-Ca2+ dimers, where Ca2+ is a diamagnetic ion.  On the basis of experimental data and by using the method described in [2], the following secular equation for finding the main values of g-tensor was obtained:  λ 3 – 13.9504 λ 2 + 64.5037 λ – 98.9219 = 0. (1)  The main values of the g-tensor are:  gzz = 2.324 ± 0.002, gxx = 2.077 ± 0.002, gyy = 2.049 ± 0.002. (2)  The main values of the g-tensor are in agreement with the structural data. Analogically, the main values of the a-tensor have been determined based on the following secular equation:  Ɛ 3 – 3.1712 Ɛ 2 +1.9952 Ɛ –0.33900 = 0. (3) The main values of the a-tensor are:  azz = (15.49 ± 0.01) mT, axx = (6.90 ± 0.01) mT, ayy = (5.45 ± 0.01) mT. (4)  The obtained data for main values of g- and a- tensors are in agreement with analogical data for the CuBa(SalH)4(DMAA)4(H2O) single crystal (see another our abstract in this Abstracts Book).