The clouding phenomenon and micellization of anionic surfactant, sodium dodecyl sulfate have been studied by measuring the cloud points (CP) of the pure surfactant and mixed system with additives such as urea and acetamide. The combined effect of these additives on cloud point measurement was investigated. The cloud point of pure surfactant Sodium dodecyl sulphate (SDS) found to be increased with increased [SDS]. The cloud point of mixed system also shows same trends with increased [Urea] and [Acetamide]. This is mainly due to increased micelle concentrations. The influence of additive, urea on the cloud point of SDS is a clear indication that the phenomenon of clouding is associated with the different micelles coalescing. The phase separation results from micelle-micelle interaction, considering cloud point as threshold temperature of the solubility, the thermodynamic parameters of clouding process (ΔGo C1, Δ Ho C1 and ΔSo C1) have been evaluated using “Phase Separation Model” Kjellander et al model according to which clouding is an entropy dominated phenomena, have also been used for calculating the thermodynamic parameters. It is found that the overall clouding process is exothermic and ΔHo C1 > TΔSo C1 indicating that the process of clouding is guided by both enthalpy and entropy. This work supports the conjecture that the cloud point is critical phenomenon rather the growth of micelles.