Thermostable vaccines promise to simplify the logistics of vaccine distribution and expand the immunization coverage. In this study, a pilot-scale spray drying process was developed and used to produce glassy state formulations of a recombinant hepatitis B (HepB) vaccine containing aluminum adjuvant and Neisseria meningitidis A (MenA) protein–polysaccharide conjugate vaccine, representing two common types of subunit vaccines in use today: the spray-dried HepB vaccine formulations were stable for at least 24 months at 37°C while several MenA vaccine formulations exhibited complete stability at temperatures up to 60°C. This study demonstrates the feasibility of producing thermostable vaccines with advanced processing and formulation technologies.