Thioacetamide (TAA) is widely used as a model of hepatic encephalopathy (HE). The aim of our study was to investigate the effects of TAA on electroencephalographic (EEG) changes in rats and to compare them with human HE. Male Wistar rats were divided into groups: (1) saline-treated group and (2) TAA-treated groups: TAA₃₀₀ (300 mg/kg), TAA₆₀₀ (600 mg/kg), and TAA₉₀₀ (900 mg/kg). Daily dose of TAA (300 mg/kg) was administered intraperitoneally once (TAA₃₀₀), twice (TAA₆₀₀), or thrice (TAA₉₀₀) in subsequent days. EEG changes were recorded about 24 h after the last dose of TAA. Absolute and relative power density in alpha bands were significantly higher in TAA₃₀₀ versus control group. In TAA₃₀₀, absolute beta power density was higher and relative beta power density was lower versus control group. Absolute alpha, theta, delta, and relative theta power were significantly lower, while relative power in delta band was significantly higher in TAA₉₀₀ versus control group ( p < 0.01). In conclusion, decrease in EEG voltage with an increase in delta relative power, which correspond to the EEG manifestations of severe HE in humans, was observed in TAA₉₀₀ group. Electrical activity in TAA₃₀₀ group correlates with mild HE in humans.