Electro-spraying/-spinning is a facile technique for the generation of nanometer to micrometer scale structures such as thin films, particles, beaded fibers, and fibers that can find a wide spectrum of applications. In this work, poly[(R)-3-hydroxybutyric acid] (PHB), which is a well-known biocompatible and biodegradable polymer, was studied with the objective of understanding the influence of PHB concentration and solvent type on the formation of the aforementioned structures when electro-sprayed/-spun. Solutions of varying concentrations of PHB (1-14 %) in chloroform, dichloroethane, and chloroform:dichloroethane (1:1) were electro-sprayed/-spun to fabricate different types of structures. It was observed that at any specific concentration, solvent properties significantly influenced formation of different kinds of structures with chloroform-based systems leading to more porous structures. Further, an increase in the concentration of PHB in solution while keeping the solvent type constant led to a gradual change in the morphology from thin films (1.5 %) to particles (1.0-2 %) to beaded fibers (3-10 %) and to fibers (14 %).Therefore, it was inferred that a variety of micro-structures of PHB can be fabricated by modulating the polymer solution concentration and solvent system. The results provide an improved understanding of the relationship between solution properties and micro-structures obtained by electro-spraying/-spinning of PHB. In addition, it also provides a method to fabricate micro-structures with diverse morphologies which can have significant implications in biomedical applications such as drug delivery and tissue engineering.