It is found on many occasions that the stability of electroless copper with formaldehyde as the reducing agent is vulnerable and so for a viable industrial process high stable plating bath is a subject of practical interest. In the present investigation, thiourea and few of its derivatives were used as stabilizers. The role of action of these compounds on the rate of electroless copper plating has been studied by weight gain, anodic & cathodic polarization and A.C impedance methods. The calculations of global reactivity indices of the additives such as the localization of frontier molecular orbital's, EHOMO, ELUMO, energy gap (ΔE) and dipole moment (μ) were used to substantiate the effective adsorption of the compounds on metal surface being responsible for stability of the bath.