BACKGROUND Biodegradable polymers of natural origin have shown great interest in release of active substances such as antioxidants as a quercetin or ascorbic acid (AA) given its interest in human health, the aim of this study is to make sure of the dissolution of this active ingredient in two reconstituted pH 1.2 (stomach) and pH 7.4, for this it is very important to choose the right matrix and the right method to prepare the good formulations, cellulose acetate is a very important polymer given its easy of obtaining by simple extraction of cotton with good yield using acetic acid and acetic anhydride. RESULTS In this work, we encapsulate AA with a mixture of polymers of cellulose triacetate (CTA) and ethylcellulose (EC) as a semi-crystalline structure by solvent evaporation method. The shape and size of the resulting microspheres were carried out by optical microscopy (OM) and scanning electron microscopy (SEM). The interactions between the active ingredient and the polymers have been studied by Fourier-transform infrared (FTIR), X-ray diffraction (XRD), proton nuclear magnetic resonance (H-1-NMR) and carbon-13 (C-13)-NMR. The results have been shown that the CTA gives a good rapid release of AA at levels relatively higher than 20% which is better in pH 7.4, this is due to the amorphous structure of the matrix used revealed by XRD. When changing the composition of the formulation (EC-CTA), the release rate of the AA is increased and has considerably modified the polydispersity and the shape of the microspheres prepared. CONCLUSION We found that the release of AA is more easily achieved in pH 7.4 medium than in the acid medium and this may suggest that this medium promotes the release of AA. The study of antioxidant activity can conclude that the encapsulation by solvent evaporation is a method which preserves the antioxidant character of the active agent using CTA as a matrix. (c) 2020 Society of Chemical Industry