New genomes of two Allochromatium strains were sequenced. Whole-genome and average nucleotide identity based on BLAST (ANIb) comparisons show that Allochromatium humboldtianum is the nearest relative of Allochromatium vinosum (ANIb, 91.5%), while both Allochromatium palmeri and Thermochromatium tepidum are more distantly related (ANIb, <87%). These new sequences firmly establish the position of Allochromatium on the family tree.