The effect of oral electrolytes or vitamin C (VC) on plasma corticosterone (PC) and adrenal gland (AG) histomorphology of heat stressed broiler chickens was evaluated in this study. A total of 200 one day-old Arbor Acre broiler chickens were allotted to five treatments in a completely randomized design. Each treatment comprised four replicates of ten chickens per replicate. Treatment 1 (T1) was the control with water without any supplement while treatments 2 (T2), 3 (T3), 4 (T4) and 5 (T5) had their water supplemented with 0.5 % ammonium chloride, sodium bicarbonate, calcium chloride and 300ppm VC, respectively. The average temperature and humidity during the experimental period ranged from 30.90ºC to 36.73ºC and 58.48 % to 89.24 % respectively. No significant variation (p>0.05) was observed in PC values among treatments at week 4. However, PC (ng/mL) values of 6.1±1.3 (control), 7.4±2.1 (NH4Cl), 5.4±0.8 (NaHCO3), 15.1±5.91 (CaCl2) and 6.4±2.4 (VC) recorded at week 7 significantly differed (p<0.05). Birds on VC supplementation had increased medullary cells (0.59/µm3 x 10-6 ± 0.12) and lowered interrenal cells (0.36/µm3 x 10-6 ± 0.18) compared to birds on other treatments. Histological changes observed in the AG of birds on control and electrolyte treatment groups revealed evidence of stress at the cellular level while a relatively normal cell appearance was observed in VC group. In conclusion, the reduction in the PC values of the ammonium chloride and sodium bicarbonate groups was similar to the observations from the control group. However, ascorbic acid maintained corticosterone concentration and prevented from the hyperplasia of interrenal cells in heat stressed birds.