A novel betaproteobacterium, strain TBEA3(T), was isolated from soil using enrichment cultures with the organic thioether 3,3'-thiodipropionic acid as sole carbon and energy source. Analysis of the 16S rRNA gene sequence revealed 99.1 % sequence similarities to a poorly characterized member of the family Comamonadaceae, strain SB1(T), which had been previously isolated from activated sludge. Both strains showed highest gene sequence similarities (up to 96.9 %) to members of the genera Rhodoferax and Curvibacter. The DNA G+C contents of strains TBEA3(T) and SB1(T) were 69.1 and 70.1 mol%, respectively, and the DNA-DNA hybridization value between these two strains was 45.3 %. The predominant cellular fatty acids in both strains were C(16 : 0), C(18 : 1)omega7c and summed feature 3 (C(16 : 1)omega7c and/or C(15 : 0) iso 2-OH). The major 3-hydroxy fatty acid was C(10 : 0) 3-OH. Based on the genetic and chemotaxonomic data, strains TBEA3(T) and SB1(T) represent two novel species of a new genus within the family Comamonadaceae, for which the name Pseudorhodoferax gen. nov. is proposed. Strain TBEA3(T) (=LMG 24555(T)=DSM 21634(T)) is assigned to Pseudorhodoferax soli sp. nov., as the type strain of the type species of the genus. Strain SB1(T) (=LMG 24543(T)=DSM 21598(T)) is the type strain of Pseudorhodoferax caeni sp. nov.