Ab initio calculations have been performed to study the structural trend, energetic stability, and fragmentation behavior of water clusters (H2O)(2-30). We show that as size increases, the cluster structures evolve from a mono-ring motif to multi-ring and ring-stacking motifs, and then to stuffed cage structures. We also show that losing water molecules one-by-one is the most favorable fragmentation channel with a dissociation energy of similar to 11.53 kcal/mol. Small water clusters such as water dimer, trimer, and tetramer, can also be observed in the fragmentation products since they often appear in the second best fragmentation channel. (C) 2011 Elsevier B. V. All rights reserved.