The Electronic absorption spectra of Co-phthalocyanine (CoPc) have been recorded with a view to study the solvent-solute interaction, H-bonding effect and its protonation in the solvents of different polarity especially in sulphuric acid of different strength. The study revealed that the CoPc acts as a weak monoacidic base in aqueous acidic solution. The hypsochromic shift of lmax was observed when concentration of sulphuric acid decreased from 36N to 6N suggesting the formation of H-bonding of H2S2O7 with atom N(2), N(3) and N(4) of CoPc and extra cyclic monoprotonation occurred irrespective to the concentration of H2SO4.