Two experiments were designed to test the hypothesis that chickens which drink on electrolyte solution (Almaril Plus) containing potassium as (citrate and dihydrogen orthophosphate) just prior and during an acute or / and chronic exposure to heat stress (HS), would have greater thermotolerance than chickens that consume only water. In two experiments (I and II) at 25 & 35 day (experiment I) and 41 - 43 day old chickens ( experiment II) drank tap water (control), or exposed to heat and drank water only, or exposed to heat and drank water contains 0.625, 1.25 and 2.00 ml electrolyte solution (Almaril Plus) / liter distilled water for 4 hours before HS and 6 hours after HS. Water and food consumption, mortality rate, body weight, Serum K, Ca and P were determined. Water and food intake increased with all concentrations in the two experiments. The concentration of 2.00 ml/ liter gave the lowest mortality rate at the age of 35 d. old chickens, and no mortalities occurred with this concentration at 25 and 41 - 43 d. Body weight (BW) was recorded weekly and 2.00 ml concentration gave the highest BW at six weeks old. The results showed that 2.00 ml concentration had no significant changes in K level at 35 d. old but showed significant increase at 41 - 43 d. old. The concentration of 2.00 ml increased Ca significantly (within normal limit) at the two experiments. At 25 and 41 - 43 d. old chickens P increased significantly (within normal limit) at all concentrations, but at 35 d. old P significantly increased with the concentration of 1.25 ml only.