Graph theory is one in all the foremost special and distinctive branch of mathematics, by which the demonstration of any structure formed is made understandable. In chemical graph theory, the edges represent the covalent bonding between atoms, and the vertices of a molecular graph represent atoms. The significance of the molecular graph is that the hydrogen atom is omitted from it.

Because of various experiments, we can claim that topological indices are useful in QSPR/QSAR studies. The correlation between physico-chemical properties (QSPR) and the biological activity relationships (QSAR) of the molecules was tested with the help of topological indices. It is pertinent to note that the topological indices have some major classes such as counted related topological indices, degree-based topological indices, and distance-based topological indices of graphs. The degree-based topological indices are very important in chemical graph theory to test the attributes of compounds and drugs, which have been mostly used in chemical and pharmacy engineering. The concept of topological indices came from the work done by Wiener while he was working on the boiling point of paraffin (an important member of the alkane family). He named this index the path number. Later, the path number was renamed the Wiener index and the whole theory of topological indices began.

The aim of this Special Issue is to attract original research and review articles discussing new methods, techniques, and computing algorithms on various theoretical and computational aspects of molecular indices. We welcome submissions from leading scientists, mathematicians, chemists and researchers working interdisciplinary areas.

Potential topics include but are not limited to the following:

• Molecular topological indices
• Application of chemical graph theory
• Graph optimization problems for topological indices
• Counting related indices and polynomials on topological indices
• Entropy of molecular graphs
• Irregularity indices of graphs
• Topological indices of nanostructures
• Algorithms and computational issues for topological indices