While writing my Chemical Graph Generators review article, I classified all the structure generators with respect to their methods. There are also two types of structure generators: open source and commercial ones. In the field of chemical graph generation, MOLGEN is the commercial but the most efficient structure generator regarding the speed and its functionalities. On the other hand, although OMG is the first open source structure generator; the field still needs a faster structure generator. In the article, different structure generators are compared with respect to their speed, mathematical basis and a lot more. This post is for the benchmark carried out for MOLGEN and OMG. Preliminaries These generators were tested 20 different molecular formulas. These formulas were randomly selected from MASSBANK and consist carbons, nitrogens, oxygens, sulfurs and halogens. The benchmarks were run in ARA cluster . The OMG jar file can be downloaded from here . MOLGEN vs OMG Be