Abstract:The effect of salinity was observed on the activity of nitrate reductase and hill reaction activity in the leaves of Cotton (Gossypium hirsutum L.) cv. "CIM 496" grown in large size plastic pot culture, irrigated with sea salt concentrations of 0.0%(EC iw: 0.6 dS/m), 0.4%(EC iw: 6.2 dS/m) and 0.8%(EC iw: 10.8 dS/m) and subjected to foliar application with nonspray (control), water spray, KNO 3 (500 ppm), KCl (500 ppm), Urea(1000 ppm), Fe-EDTA (5ppm), MnCl 2 (5ppm) and MoO 3 (5ppm) alone and their mixture. Foliar spray of the mixture showed better result as compared to that of above mentioned individual mineral. Conclusion made on the comparative performance of nitrate reductase and hill reaction enzymes under above number of treatments in the leaves of cotton growing under various sea salt concentrations is given below: Nitrate Reductase Activity (NRA): Nonspray< water spray< KCl< Mo< KNO 3 < Urea< KNO 3 + Mo< KNO 3 +Fe + Mn + Mo; Hill Reaction Activity (HRA): Nonspray< water spray< KNO3