The use of water of dubious quality in irrigation can be harmful to plants, so the aim of this work is to assess the effects of salinity and the chemical composition of irrigation water on growth, gas exchange, mineral nutrition and the levels of organic solutes in cowpea plants [Vigna unguiculata (L.) Walp.] cv. Pitiúba. The plants were grown in pots in a greenhouse and subjected to 4 different electrical conductivities of the irrigation water. During the experimental period, the transpiration rate, net photosynthesis rate, chlorophyll content and stomatal conductance were measured, as well as analysing the electrical conductivity of the percolated water and the substrate, in addition to the morphological characteristics of the plants, showing their development when subjected to the salinity of the irrigation water.