||The aim of the present study was to prepare microspheres containing Isoniazid, using Chitosan, Hydroxypropyl methylcellulose (HPMC) and Hydroxypropyl cellulose (HPC) as carrier polymers to achieve aerodynamic properties with sustainable drug release in lungs. The microspheres were evaluated for morphological characterization, particle size analysis, and differential scanning calorimetry and in-vitro deposition studies. The microspheres were spherical shaped with slight rough surface and appeared as aggregated particles, however, HPMC-microspheres found to have collapsed surface. The in vitro drug deposition revealed that mass median aerodynamic diameter of microspheres was in the range of 2.53 to 3.01μm with fine particle fraction between 44-66%. All the formulation batches showed acceptable drug loading (> 90%), powder flow properties having Carr’s index in the range of 30 to 44 %. Microspheres showed sustained drug release over period of more than 8 hours except HPC-microspheres. The microspheres prepared with spray drying technique showed promising aerosol properties with sustained drug release properties required for effective pulmonary administration of isoniazid.