The photocatalytic behaviour of TiO 2 has been thoroughly investigated the past years using UV light to photoactivate TiO 2 . As this method introduces complications making it difficult to do it economically viable, new pathways to activate TiO 2 have been sought. In the present work, reactive oxygen species (ROS) were obtained in a suspension of hydrogen peroxide (H 2 O 2 ) and titanium dioxide (TiO 2 ) in darkness, offering an alternative method to initiate oxidative behaviour of TiO 2 . Methylene blue (MB) degradation was chosen as an indicator for measuring the catalytic effect, allowing for a comparison of the reaction kinetics with other methods to create ROS with TiO 2 . The effects of TiO 2 particle effective surface area and concentration of H 2 O 2 were also studied. EPR studies were made to determine the presence of free radicals in the mixture of TiO 2 /H 2 O 2 in darkness. Under the given lighting conditions, the results demonstrate the relevance of the TiO 2 effective surface area and concentration of H 2 O 2 and TiO 2 as parameters influencing the chemical catalysis of MB due to the action of hydroxyl (OH) and/or hydroperoxide radicals (HO 2 ).