Gluten-free producers face signifcant technical and nutritional challenges, technological challenges due to lack of gluten. Cantaloupe by-products (CB) contain dietary fber-associated phenolic compounds in different proportions. This study examined a new gluten-free donut (GFD) supplemented with antioxidant dietary fber made from cantaloupe by-products (ADF-CB). Using response surface methodology (RSM), the efect of ADF-CB incorporation level (5–20 g/100 g rice four) at particle sizes (PS) (75–500 μm) on pasting physicochemical and sensory properties of the experimental GFDs were investigated. The optimal condi tions for producing high sensory scores to control were: 18 g/100 g rice four at PS 438 µm (T4); 20 g/100 g rice four at 288 µm (T1) and 13 g/100 g rice four at 500 µm (T2). At these conditions, dietary fber content increased by about fourfold higher than the control. Total phenolic content (TPC) increased by about ninefold higher than that of the control. Antioxidant properties exhibited as tested by IC50, which decrease by half-fold against the control. Oxygen radical absorbance capacity (ORAC) assay exhibited a signifcant increase by more than 8- folds higher than that of the control. Pasting properties values were increased as ADF-CB and PS increased except Setback viscosity (SBV). The use of ADF-CB with indicated PS to enhance the nutritional characteristics of GFD on an industrial scale as a health-promoting functional ingredient in gluten-free products