Spinach (Spinacia oleracea L.), as well as the New Zealand spinach (Tetragonia tetragonoides (Pall.) o. Kuntze syn. (Tetragonia expansa)), is nutritional valuable leafy vegetable. Alongside with therich content of vitamins and minerals mentioned leafy vegetables are also known to have the significant antioxidant potential. Spinach tends to accumulate nitrogen, therefore should be careful during fertilization and consummation. Unlike the spinach, the New Zealand spinach is in our region relatively unfamiliar and new species, but as well as spinach contains a significant amount of vitamins, minerals and other phytonutrients. Although the above mentioned species are mainly grown in the soil, can also be grown in hydroponic system such as in the floating containers system. The aim of this thesis was to determine nutritional value and content of biologically active compounds in spinach and New Zealand spinach grown in floating hydroponics with nutrient solutions of different nitrogen concentrations in nutrient solutions. The nutrient solutions were: a standard solution, a nutrient solution with a concentration 75 mg/L NH4NO3, 140 mg/L NH4NO3 and 205 mg/L NH4NO3. The highest total dry matter content was determined in spinach grown in the standard solution. From the studied bioactive compounds, the highest amount of vitamin C content was determined in spinach grown in standard solution. Significantly higher content of total phenols, chlorophylls, carotenoids and antioxidant capacity shows spinach compared to New Zealand spinach. Spinach shows considerably higher values of nutritional composition when cultivated in the standard solution, while the nutritional composition values are reduced by increasing the concentration of nitrogen in nutrient solution. New Zealand spinach had higher values of nutritional composition by increasing the concentration of nitrogen in nutrient solutions.