The aim of this paper was to investigate the influence of preparation parameters on gelatin microspheres production, chemico-physical characteristics and drug encapsulation. In particular, we focussed our attention on the manufacturing parameters such as amount of polymer, stirring speed, presence and concentration of surfactants. As model drugs, TAPP-Br, clonidine hydrochloride and bromocriptine mesylate were chosen in order to compare their encapsulation and release characteristics with microspheres. In the second part of this work, a study of the influence of thermal treatment on the microspheres is reported, performed with the aim to possibly modify gelatin dissolution and drug release. In particular, the effect of this treatment was evaluated on microsphere characteristics such as swelling, porosity and dissolution, and finally on the release profiles of the encapsulated drugs.