Two field experiments were conducted at Skis Agricultural Research Station, during 2004 and 2005 seasons, to study the response of cotton plant, Giza 80 to the application of methanol under two levels of irrigation (15 and 21 days Intervals). Methanol sprayed at concentrations of (0, 5, 10, 15 and 20 % V/V) one time at the start of flowering. Results could be summarized as follows : Foliar application of methanol increased number of fruiting branches I plant, specific leaf area (51A), number of open bolls / plant, boll weight, seed index, lint percentage, seed cotton yield per feddan, fiber fineness, fiber strength and fiber length than the control. The highest values of seed cotton yield per feddan were obtained from applying methanol at the concentration of 20 % (30.29 and 24.41 %) in both seasons respectively more than the control. Also, a, b and total chlorophyll, carbohydrates and phenols in leaves and protein and oils in seeds were increased as a result of methanol application. Exceeded irrigation interval of 21 days indicated a reduction in number of fruiting branches / plant, leaf area index (Iii1), and weight (SLW), number of open bolls / plant, boll weight, seed index, lint %, yield per feddan, fiber fineness, strength and length of cotton plant (Giza 80 aitivar), and all the chemical components studied. Methanol application under water stress (irrigation intervals of 21 days each) reduced the damage effect of water stress and led to an increase of chlorophyll contents, carbohydrates and phenols in leaves, this caused an Increase in open bolls / plant and boll weight and effect proportionally on the yield of seed cotton / feddan. Methanol at 20 % with 15 days interval treatment exhibited the highest values of all the pervious characteristics than those of control.