Disposal of tire rubber is an environmental challenge in many countries. It has recently been shown that rubber can be used as an effective source of zinc (Zn) and some other nutrients for crops. According to the previous results, rubber particles size is a key factor determining the rate of micronutrient release from the rubber wastes. In this study, different treatments were applied to synthesis Zn nano-particles from waste tire rubber. Scrap tire was reduced to 3mm shreds by a slow speed shredder. The particles were processed to smaller sizes by grinding rolling mills and sieved on a stainless steel sieve ( 0.1 mm screen). Waste tire rubber, 100 µm particles were milled for 5 or 10 h inside ball mill with bullet: powder ratio of 1:10 at 500 rpm individually or in combination with different ratios of liquid nitrogen, silicon wastes or steel wastes. A rubber ash sample was also produced by ashing ground tire rubber in a furnace at 550°C for 12 h. The particles produced after applying various treatments were characterized using scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The SEM results confirmed successful synthesis of nano-particles ( 100 nm) from waste rubber or rubber ash by milling (for 5 h) in the presence of silicon wastes. The XRD analyses showed that rubber ash contained about 10% Zn while negligible Cd and Pb contents. On the other hand, the extractability of Zn from waste rubber at nano-size was significantly greater than those at 100 nm size. Results showed that rubber ash at nano size has more than 40% zinc that is much higher than the ash in the micron size. According to the results, the best approach for synthesis of nano-Zn particles from waste tire rubber is milling them inside ball mill for 5 h in the presence of silicon wastes. In the next step, the efficiency of rubber nano-particles as Zn source for cucumber in nutrient solution culture was compared with ground tire rubber and a commercial ZnSO 4 fertilizer. The cucumber seedlings grown in nutrient solution containing nano-Zn particles had higher shoot growth and accumulated higher amounts of Zn in their tissues compared with those grown in ZnSO 4 -containing nutrient solution. The imaged taken by TEM confirmed the penetration of nano-particles of rubber into the root cells. The filaments of nano-rubber particles were also observed at the end of roots by LM and TEM. According to the results obtained, nano-zinc particles synthesized from waste tire rubber offer strong value as Zn fertilizer for cucumber grown in the nutrient solution culture. Further research is needed to clarify the fate of these nano-particles in the plant cells and their possible harmful effects of food chain. Keywords: Zinc, Iron, Cadmium, Lead, Waste tire rubber, Nano-Zn particles, Cucumber