Abstract: Background and Objective: Cobalt is a naturally-occurring trace element with a wide range of industrial and medical applications. In daily life, humans are exposed to Cobalt through inhalation, drinking water and food. The study investigated the effects of cobalt chloride on the cerebral cortex in Wistar rats. Materials and Methods: Thirty-Six healthy adult Wistar rats of both sexes weighing 170-220 g were separated into four groups, A, B, C and D with each group containing nine animals. Group A rats were the control, while group B, C and D were treated orally with Cobalt chloride 66.8, 145 and 223.2 mg kg–1 body weight for 23 days, respectively. The rats were sacrificed and the brain was removed and weighed using a sensitive weighing balance, part of the brain was homogenized for biochemical analysis for MDA. The SDH and NO, while the remaining part was fixed in 10% formol calcium and processed for histological study. Results: The mean body weights of the Wistar rats decreased significantly (p<0.05) in groups B, C and D treated groups compared with Group A. The brain weights in groups B, C and D treated groups also decreased insignificantly (p>0.05) when compared with group A biochemical analysis indicated a significant increase (p<0.05) in the level of MDA while SDH and NO levels were significantly reduced (p<0.05) in group B, C and D treated groups as compared with group A. Histological study of the cerebral cortex revealed that the cerebral cortical layers in groups C and D appeared distorted and degenerated in a dose-dependent manner as compared with group A which shows a normal cerebral cortical architecture. Conclusion: The cobalt chloride administration has a neurotoxic effect on the cerebral cortical layers in adult Wistar rats which may adversely affect some cerebral cortical functions.