The aim of the present study was the preparation of aerogel microspheres based on alginate and hyaluronic acid for the potential application in pulmonary drug delivery. Both polymers are commonly used in the pharmaceutical and medical fields because of their nontoxicity, biodegradability and biocompatibility characteristics. The bio-based microspheres were produced using an emulsion gelation process with a subsequent drying step by supercritical CO2. The microspheres were characterized by FTIR and SEM. Furthermore, their BET surface area, particle size distribution, and their aerodynamic properties were determined. The microspheres showed a low density in the range of 0.035- 0.063 g/cm(3) and a high porosity of 97.6-98.7 %, as well as good in vitro aerodynamic properties with dA values of about 5 mu m. The obtained properties of the alginate- hyaluronic acid microspheres suggest that they are potentially suitable as drug carrier for pulmonary delivery. (C) 2019 Elsevier B.V. All rights reserved.