We report the cosynthesis of highly stable laminated single crystal alpha- and beta-Co(OH)(2) using the reaction and diffusion of a hydroxide solution into a gel containing Co(II). The obtained alpha-Co(OH)(2), which is known to be thermodynamically unstable and transforms in a short period of time to the P form, has been stabilized in the gel medium for weeks. The system also exhibits Liesegang banding where complicated spatial dynamics during the formation of the two polymorphs are shown to take place.