The aim of this study was to investigate the effects of two bleaching systems on micro hardness, surface roughness and color stability of two novel dental composites. Ormocer based restorative Admira and nano-filled composite Clearfil Majesty Esthetic were bleached with 10% carbamide peroxide(Opalescence PF) or 35% hydrogen peroxide(Beyond Max 5) and subsequently immersed in four different staining solutions(coffee, tea, red wine, and cola). Distilled water was used as a control. Color measurements were performed with a spectrophotometer. Vickers micro hardness and roughness data were analyzed with twoway analysis of variance for repeated measures. The analysis of variance was used to compare the color change values. Duncan’s multiple comparison test was applied to compare the results(α = 5%). ΔEab* values over 3.3 were considered clinically unacceptable. Micro hardness and surface roughness values of the tested composites were decreased significantly after bleaching applications. Red wine and tea storage caused perceptible discolorations in the composite resin materials after 30 days of 3-hour immersion. Home or office bleaching applications can affect the surface properties of resin composites and accelerate the staining process. The aim of this study was to investigate the effects of two bleaching systems on micro hardness, surface roughness and color stability of two cold dental composites. Ormocer based restorative Admira and nano-filled composite Clearfil Majesty Esthetic were bleached with 10% carbamide peroxide (Opalescence PF) or 35% hydrogen peroxide (Beyond Max 5) and subsequently immersed in four different staining solutions (coffee, tea, red wine, and cola). Color measurements were performed with a spectrophotometer. Vickers micro The analysis of variance was used to compare the color change values. Daban’s multiple comparison test was applied to compare the results (α = 5%). ΔEab * values ​​over 3.3 were considered clinically unacceptable. Micro hardness and surface roughness values ​​of the tested composites were decreased significantly after bleaching applications. Re d wine and tea storage caused perceptible discolorations in the composite resin materials after 30 days of 3-hour immersion. Home or office bleaching applications can affect the surface properties of resin composites and accelerate the staining process.