The formation of spherical, cylindrical, and bilayered vesicle structures from dispersions of polyethylene oxide)-b-poly(γ-methyl-ε-caprolactone) (OMCL) in water, is discussed. These structures were generated at moderate temperatures without the use of a cosolvent and are comprised of a hydrophilic, biocompatible poly(ethylene oxide) block and an amorphous poly(γ-methyl-ε-caprolactone) (PMCL). Aqueous solutions of OMCL diblocks were prepared by a thin-film hydration protocol in which OMCL was initially dissolved in methylene chloride and the solution was added to tared vials. Solution morphologies were characterized with cryogenic transmission electron microscopy (cryo-TEM) which allows direct visualization of the aggregate structures formed in water. The results of the study identify a promising approach for producing biocompatible and biodegradable dispersions under physiological conditions.