A first experimental demonstration of a planar superprism in silicon microphotonics technology using silicon on insulator (SOI) substrates is presented. Experimental results for anomalous wavelengthdependent angular dispersion in SOI triangular lattice planar photonic crystals are reported. An angular swing of 14 degrees is measured for light propagating near the Gamma-K direction as the input wavelength is changed from 1295 nm to 1330 nm, which corresponds to an angular dispersion of 0.4 degrees /nm. For the Gamma-M direction, a negative wavelength dispersion has been recorded. An opposite sign angular deviation of 21 degrees is observed as the input wavelength is changed from 1316 nm to 1332 nm, i.e. a dispersion of 1.3 degrees /nm.