An attempt was made to study the effect of presence of inorganic salts namely, sodium carbonate, sodium chloride and sodium sulphate, and their concentrations on decolouration of acid dye effluent by ozonation. Studies have been conducted at different salt concentrations and at alkaline pH on Acid Black 1 dye effluent, having a concentration of 500 muM. It has been found that salt content in the effluent increases the decolouration time of the acid dye effluent. Higher the salt content more is the decolouration time and among the salts, sodium carbonate requires more time for complete decolouration than the sodium chloride and sodium sulphate. Chemical oxygen demand (COD) reduces by 52, 58 and 62% whereas total organic carbon (TOC) reduces by 28, 32 and 33% for the salt present in the effluent, namely sodium carbonate, sodium chloride and sodium sulphate respectively. IR spectra study confirms the formation of acidic by-products during ozonation.