In this paper we study a superprism effect in a low contrast volumetric photonic crystal. The photonic crystals considered in the simulations have hexagonal lattices and a refractive index difference of 0.1 for double glass crystals and 0.6 for air-glass structures. The simulations show the existence of a superprism effect in both types of structures for an incident wavelength of 850 nm. In both cases various linear fill factors are studied in order to maximize the frequency range of a superprism effect. In a double glass structure, the maximum normalized frequency range is equal to 0.012, while for the air glass structures it reaches 0.108. © 2009 Photonics Society of Poland.