The objective of the present paper is to investigate the mechanism of MCs+ molecular ion production with variable Cs impact energy by examining the emission of various atomic and molecular ions from the surface of elemental molybdenum when bombarded with Cs+ under secondary ion mass spectrometry (SIMS) study. Increasing primary ion energy is accompanied by a monotonic rise in MoCs+ molecular ion intensity. The observation is explained by the difference in the surface work function (ϕ) and fractional surface concentration (cCs) brought on by different impact energy. It appears that ϕ is linearly dependent on cCs. To explain the MoCs+ data, a phenomenological model has been used, which is based on ϕ's linear dependency on cCs.