The research of this doctoral dissertation, was based on the extraction of proteins from the by-products of vegetable processing – green leaves, with the aim of examining their functional and biological characteristics, as well as the development of new formulations of food products based on these proteins. Emphasis is placed on the valorization of by-products of the agroindustry that are created after growing and picking vegetables in order to obtain new proteins.Research was conducted on proteins obtained from the leaves of cauliflower, broccoli, cabbage and beets. In the first phase of the research, leaf proteins obtained using alkaline extraction were characterized in terms of functional and biological properties, their digestibility was examined, as well as the antioxidant potential of the obtained hydrolysates.In the second phase, research is based on the improvement of the leaf protein extraction process using ultrasonic and enzymatic pretreatment, and the efficiency of the extraction is monitored by examining the functional and physical characteristics of the obtained leaf proteins.In the third phase, research was conducted with a focus on the incorporation of broccoli leaf protein as a functional additive in the food matrix with the aim of obtaining a new product, and testing its physical-chemical, structural and sensory properties, in vitro digestion and antioxidant potential after digestion.The results presented in this doctoral dissertation constitute scientific knowledge about the application of techniques for extracting protein from green leaves, and also about obtaining food products with improved biological and nutritional properties that can respond to the increasing demands and needs of consumers for functional food.