The formation of metastable bcc phase at high temperature ordering of micelles was investigated. Anionic polymerization was used to synthesize a symmetric poly(styrene-b-isoprene) (SI) diblock copolymer. The metastable bcc phase nucleated first upon heating and then it transformed over the time to the stable fcc phase. The fcc phase was found to transform into an equilibrium bcc phase at higher temperatures. The results show that bcc nucleates more readily from a melt of spheres.