C-C bond formation in a regiospecific and atom economic manner has been a challenge, which was tried to be resolved through directing group and organometals-based C-H activation strategy. The C-H activation and its advantages are well explored in the field of organic chemistry, with the relevant mechanistic approach of the regioselective C-H activation of the aryl group. Organometals like Ru, Pd, Pt, Ni, etc have been best discovered for the innate C-H activation where the pre-activation of the inert C-H bond was not found necessary. In the progress of these reactions through organometals, the various forms of ruthenium have been tried with the different directing groups as well as the substrate. Here in we are focusing mainly oncationic ruthenium, and its use in the C-H activation. The cationic ruthenium shows unique characteristics like reactivity with an inert substrate, which is been highlighted here in the examples. The formation and its, mechanistic role is also exemplified with the diagrammed representation of C-H activation and its catalytic cycle. The application of the cationic ruthenium will give complete knowledge about cationic ruthenium and its application in C-H activation.