Rational cubic spline with tension [Gregory and Sa fraz'90] is generalized to form a parametric surface interpolant to a given rectangular set of points. A simple cardinal product method is presented which is equivalent to forming a network of interpolatory rational cubic tension spline curves through the data points. This is different from the cardinal product approach of Foley and Ely [Foly and Ely'89] since the shape parameters involved in our approach are variable whereas in (Foley and Ely'89) they are not. Moreover, our cardinal product technique produces a C2 surface and the practical way which attempts to compute the surface method is nearly C2, but the surface in [Foley and Ely'89] is only C1.