The members of family Aquificaceae are generally belong to microaerophilic, chemolithotrophic or aerobic bacteria. They grow at thermophilic condition and are capable of surviving in extreme environments. The detail molecular organization of these bacteria has not been reported yet with clarity that we normally expect. Their genomes are characterized by having rather low GC-content. In order to figure out, within their genomes, a common molecular signature, the Codon usage profiles, Correspondence analysis (COA) and Codon adaptation index (CAI) values were calculated. Furthermore, a few physical parameters, such as the number of genes present in genome, highest length of gene (bp), average length of gene, lowest length of gene (bp), habitat or place of isolation, optimum growth temperature (°C) genome size (Mb were taken into account. An overall uniformity was observed in all the genomes except for Hydrogenivirga sp [128-5-R1-1], which has a relatively large genome and possesses a mesophilic growth habit. BLAST result of 16 s r-DNA genes and t-RNA synthase genes of this species, revealed that some of the genes are related to Aquificaceae while some other genes are related to Hydrogenothermaceae. It also appears to possess two kinds of GC values. The genes are aggregated in two patches as was revealed through correspondence analysis plot. The present study aims at elucidating the interrelationships between the life style and that of G + C content in these microorganisms. © 2018 Elsevier Inc.