The objective was of the study were to examine different concentrations of hydrogen peroxide on some fruit quality parameters and yield of watermelon from individual grafted and ungrafted seedlings. The field trials were performed in four concentrations of hydrogen peroxide (H O-2(2) + C2H4O2) and in combination of phosphorus pentoxide (P2O5 + K2O) in 2010 and 2011, consequently. In the experiment 300 ml/100 L and 400 ml/100 L H2O2 + C2H4O2 alone, and combination with 60 ml/100 L and 80 ml/100 L P2O5 + K2O were used in flowering, first fruit setting and when fruit size was 10-12 cm in diameter for both years. The results revealed that combination of H2O2 + C2H4O2 and P2O5 + K2O foliar applications improved yield significantly both per plant and total in grafted and ungrafted plants in the two years. Besides, such combinations also enriched total soluble solid content in grafted and ungrafted plants. However, those increases appeared more comparable in grafted ones. In addition, fruit thickness, titratable acidity (TA) and flesh colour (a*/b*) were considerably affected by all applications of hydrogen peroxide.