This study investigated the effect of various amino acids on the molecular and thermodynamic stability of IgG (immune globulin G) as well as its aerosol performance. The antibody was spray-dried in the presence of different amino acids (leucine, phenylalanine, cysteine, glycine, lysine and arginine) using 20% and 50% (w/w) amino acid. SEC-HPLC, SDS-PAGE and IR-spectroscopy were performed to evaluate the stability of spray-dried IgG. The in-vitro aerosol performance of the well-stabilized formulations was subsequently assessed. IgG containing phenylalanine at 20 and 50% w/w produced the lowest content of aggregated antibody (1.35 ± 0.24%) and (1.12 ± 0.15%). The application of phenylalanine and cysteine at 50% (w/w) demonstrated the best storage stability (2 month at 45 °C) with a rate constant of 0.006/month and enhanced fine particle fractions of 62.43 ± 0.34% and 70.51 ± 0.23%, respectively. Samples containing 50% arginine exhibited significantly perturbed conformation and, consequently, the highest aggregation rate constant of 0.019/month following storage. These results indicate that phenylalanine and cysteine serve as efficacious amino acids for the preparation of IgG dry powder with regard to stability and aerodynamic properties.