Titanium　dioxide　(TiO2)　nanoparticles　were　synthesized　by　controlled　hydrolysis　of　titanium　alkoxide　in　reverse　micelles　in　a　hydrocarbon　solvent.　Upon　annealing　in　situ　in　the　presence　of　the　micelles　at　temperatures　considerably　lower　than　those　required　for　the　traditional　calcination　treatment　in　the　solid　state,　the　TiO2　nanoparticles　became　highly　crystalline　but　still　maintained　the　same　physical　parameters　and　remained　in　a　stable　suspension.　Thus,　the　method　has　allowed　the　preparation　of　crystalline　TiO2　nanoparticles　that　are　monodispersed　in　the　same　way　as　they　are　initially　produced　in　the　microemulsion.　Effects　of　the　fluid　properties　on　the　crystallization　of　nanoparticles　are　discussed.