Concentrated hydrogen peroxide (H2O2) intoxication is relatively rare in children. Serious irreversible neurotoxicity generally results. The case of an 11-year-old boy who inadvertently drank a concentrated (35%) H2O2 solution is described. He exhibited signs of an acute encephalopathy with cortical visual impairment. Extensive cerebrocortical diffusion restriction with apparent gyral edema was evident at 3 days following ingestion, particularly in the parieto-occipital regions bilaterally. Spontaneous neurologic improvement quickly followed, and nearly full clinical resolution was evident 1 month later. The pattern of imaging abnormalities closely resembles that of reversible posterior leukoencephalopathy. Concentrated H2O2 neurotoxicity in children can exhibit unique patterns (a reversible posterior leukoencephalopathy) and a better than expected outcome.