Cotton (Gossypium hirsutum L.) plants were grown hydroponically in a controlled environment. Sodium chloride was used to induce three osmotic stresses: low (0 atm), medium (6 atm), and high (12 atm). Leaves of approximately the same age were harvested 49 days after planting from five replications of each treatment, and their reflectance and transmittance spectra were obtained for the wavelength interval 500‐ to 2,500µ Osmotic stresses of 6 and 12 atm reduced reflectance and increased transmittance of near‐infrared light (750 ‐ 1,350 mµ) as compared with leaves from plants grown with low osmotic stress. Tissue sections from the same leaves were processed to provide transverse sections for histological examination; leaves from plants grown with 6 and 12 atm of osmotic stress exhibited a more compact cell arrangement than nonosmotically stressed leaves.