Experimental results are presented concerning the zero frequency and dynamic properties of a cross-linked polysiloxane near gelation threshold. It is prepared by hydrosilation of a difunctional vinyl-terminated polydimethylsiloxane prepolymer and a seven-functional poly(dimethylsiloxane-co-methylhydrogenosiloxane) prepolymer. The zero frequency and dynamic properties during cross linking have been studied by rheological experiments in the framework of the linear viscoelasticity. The material at the gelation threshold follows a power law viscoelastic behavior, G* proportional to omega (u) with u = 0.77. The zero frequency exponents s and t (eta proportional to epsilon (s); G proportional to epsilon (t)) were determined from the theological data (s = 0.76 and t = 2.54). This study shows that the zero frequency and dynamic exponents obey to the scaling relation u = t/(s+t) and are not universal. Above the gelation threshold, a theological master curve could be built showing that the viscoelastic properties of the gel are governed by the molecular structure of the prepolymers and the self-similarity of the mass distribution of clusters. In this way, this system follows the percolation theory. Assuming that the nonreacted prepolymers swell the network, the molecular weight between crosslinks was estimated.