The recovery of antioxidant compounds present in sunflower hulls, a waste byproduct of the oil extraction process, can be of industrial and environmental interest. The objective of the present work was to determine different operating conditions for the extraction of phenolic compounds from hulls oil sunflower seeds, using water at 90 °C and mechanical agitation. To select the experimental conditions, the hulls of a black hull sunflower hybrid (SPS3120) were analyzed, five particle sizes (>0.84, 0.84 to 0.42, 0.42 to 0.25, 0.25 to 0.149, <0.149 mm), three pH values (5, 7 and 9) and samples with and without oil were evaluated. The selected conditions (pH 9, fractions of particle size ≤0.25 mm- approximately 24 % of the hull, with a prior removal of the oil) were also applied to other three black-oil hybrids (SyN3840, SyN3950, DK4065) and two striped sunflower hybrids (CF201, PAN7077), evaluating the total phenol content and total flavonoid content in the fractions of particle size ≤0.25 and >0.25 mm. By processing approximately 23-24 % of the sunflower hull (≤0.25 mm particle-size fraction), it was possible to obtain a minimum of 59 and 62 % of total phenols and total flavonoids of the total hull, respectively, under the selected conditions. DOI: https://doi.org/10.54167/tch.v16i3.1023