Graph operations are essential in many graph theory applications because they enable the creation of large graphs from smaller ones. This study focuses on a particular graph-theoretical operation: the Cartesian product graph. Our research is focused on alkanes, the simplest hydrocarbons made only of hydrogen (H) and carbon (C) atoms with no functional groups. In this paper, we compute several topological indices for the Cartesian product of alkanes namely, Atom Bond Connectivity Index ( ABC), Geometric Arithmetic ( GA ), Randic Index ( ), Reciprocal Randic Index ( RR ), First Zagreb Index ( ), Second Zagreb Index ( ), Hyper Zagreb Index ( HM ), Forgotten Index ( F ), Inverse Sum Indeg Index ( ISI ), Symmetric Division Deg Index ( SDD ). Additionally, we provide a graphical and numerical comparison of these topological indices.