The need to have unified 3D datum transformation parameters for Nigeria for converting coordinates from Minna to WGS84 datum and vice-versa in order to overcome the ambiguity, inconsistency and non-conformity of existing traditional reference frames within national and international mapping system is long overdue. This study therefore develops the optimal transformation parameters between Clarke 1880 and WGS84 datums and vice-versa for Cross River State in Nigeria using the Molodensky-Badekas model. One hundred (100) first order 3D geodetic controls common in the Clarke 1880 and WGS84 datums were used for the study. Least squares solutions of the model was solved using MATLAB programming software. The datum shift parameters derived in the study were ΔX = 99.388653795075243m ± 2.453509278, ΔY = 15.027733957346365m ± 2.450564809, ΔZ = -60.390012806020579m ± 2.450556881, α = -0.000000601338389±0.000004394, β = 0.000021566705811 ± 0.00004133728, γ = 0.000034795781381 ± 0.00007348844, S(ppm) = 0.9999325233 ± 0.00003047930445. The results of the computation showed roughly good estimates of the datum shift parameters (dX, dY, dZ, K, RX , RY , RZ, K ) and standard deviation of the parameters. The computed residuals of the XYZ parameters were relatively good. The result of the test computation of the shift parameters using the entire 107 points were however not significantly different from those obtained with the 100 points, as the results showed good agreement between them. Seven reserved points (xsw148, xsw117, xsw126, xsw97, xsw82, xsw64, xsw155) were used to validate the model.
