We have carried out cyclic voltammetric and electrochemical impedance spectroscopic studies to compare the barrier properties of monolayer on gold formed by two alkanethiols of different chain lengths in solvents like acetonitrile, propylene carbonate, ethanol and formamide. Our results show that the blocking behavior of the alkanethiol monolayer to ferrocene electron transfer reaction varies in the order formamide > ethanol > acetonitrile congruent to propylene carbonate. The electron transfer through the monolayer is facilitated by the ability of the solvent molecules to interact with the thiol molecules and disorganize the monolayer. We have correlated the internal order of the solvent molecules with their ability to influence the structural integrity and barrier properties of the monolayer.