Metal encapsulated silicon clusters M@Sin (M = Ti and Cr and n = 8-16) have been studied using ab-init ultrasoft pseudopotential method. Several structures for each cluster have been optimized to obtain the lowest energy isomers. Our results show that cage strucntures begin to form at the size of n = 12 for Cr@Sin and 13 for Ti@Sin. For Ti@Sin our results are in excellent agreement with the available experimental results. In smaller size, metal doped silicon clusters have basket structures to be of the lowest energy. The bonding nature in these clusters is discussed from the electronic charge distribution.