Two bacterial isolates, designated strains 5420S-26(T) and 5516S-1(T), were recovered from air samples collected in Suwon, Korea. Cells of both strains were aerobic, Gram-negative, motile rods. Phylogenetically, these strains were positioned within the radius of the genus Massilia. 16S rRNA gene sequence analysis showed that the strains shared 97.3 % sequence similarity and had sequence similarities of 94.9-98.1 % with respect to type strains of species belonging to the genus Massilia. In DNA-DNA hybridization tests, the two strains showed <39 % relatedness with respect to strains of closely related species of the genus Massilia and 27 % relatedness to each other. Both strains contained Q-8 as the predominant isoprenoid quinone and possessed summed feature 3 (comprising C(16 : 1)omega7c and/or iso-C(15 : 0) 2-OH) as the major fatty acid. Strain 5516S-1(T) was found to contain the fatty acid C(20 : 0) (in small amounts), a feature that served to distinguish it from both 5420S-26(T) and recognized members of the genus Massilia. The DNA G+C contents of 5420S-26(T) and 5516S-1(T) were 67.8 and 66.6 mol%, respectively. Phylogenetic, phenotypic and chemotaxonomic data accumulated in this study revealed that 5420S-26(T) and 5516S-1(T) represent novel species of the genus Massilia, for which the names Massilia niabensis sp. nov. (type strain 5420S-26(T) =KACC 12632(T) =DSM 21312(T)) and Massilia niastensis sp. nov. (type strain 5516S-1(T) =KACC 12599(T) =DSM 21313(T)) are proposed, respectively.