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We investigate the influence of Ca ions on the structural and superconducting properties of (Nd1−yCay)Ba2(Cu0.94Ga0.06)3Oz system by Rietveld refinement of the neutron diffraction patterns of three samples with y = 0.0 (A1), y = 0.18 (A2), and y = 0.36 (A3) along with X-ray diffraction, resistivity, and ac susceptibility measurements. Samples A2 and A3 are superconducting with Tc values of 37 K and 76 K, respectively, whereas sample A1 is semiconducting to 20 K. Neutron diffraction data confirms (a) the occurrence of a single-phase tetragonal structure (space group Pmmm) for all three samples; (b) Ca ions substitute at the Nd site; and (c) increasing y from 0.0 to 0.36 decreases Cu(1)-O(1), Cu(2)-O(2), and Nd-Cu(2) bond lengths, whereas Cu(2)-O(4) bond length increases with corresponding increase in Tc to 76 K due to increasing occupancy of Ca ions at Nd site. A correlation exists between the Cu(1)-O(1), Cu(2)-O(2), Cu(2)-O(4), and Nd-Cu(2) bond lengths and the measured Tc values of three samples.