Copper (Cu) is an essential micronutrient for higher plants and is required for cell redox homeostasis, free radical scavenging, function of electron transport chains and cell wall lignification. Copper deficiency is a widespread nutritional disorder in plants and its adequate supply is necessary for an optimum crop production. In order to evaluate the efficacy of nano tetraammine copper (II) sulfate complex ([Cu(NH3)4]SO4) (NCu) in the meeting of plants Cu requirement, Cu-sufficient (+Cu) and Cu-deficient (–Cu) tobacco (Ncotiana rustica L.) plants were treated with 0.5 µM NCu complex through leaves. The shoot and root biomass and photosynthesis of –Cu plants were restored by foliar application of NCu complex, while in the +Cu plants the shoot biomass was repressed likely due to a supra optimal Cu level. Foliar application of NCu complex restored almost completely the activity of Cu-containing enzymes, superoxide dismutase, polyphenol oxidase and diamine oxidase. Iron (Fe) homeostasis was also significantly influenced by both Cu starvation and foliar application as could be confirmed by Fe concentration data and activity of Fe-enzymes, peroxidase and polyamine oxidase. The activity of phenylalanine ammonia lyase and the levels of phenolics and lignin were markedly decreased in the –Cu plants. These parameters, however, were completely restored or even exceeded that of the +Cu plants upon foliar application. Our results suggest that, foliar application of NCu is a feasible method for a rapid and efficient compensation of Cu deficiency symptoms due to a high penetration ability and a sufficient retranslocation of applied Cu in the phloem.