Branching ratios for 3d 8 4p → 3d 8 4s lines of Ni II have been determined from measurements of emission-line intensities in an optically thin laser-produced plasma. The present values have been compared with the data available in the literature and are in good agreement. Calculations with intermediate coupling using Hartree-Fock wavefunctions have been carried out in order to place the experimental data on an absolute scale. The plasma parameters in different regions of the plasma plume have been measured and used to obtain further transition probabilities.