The aim of the present study was to prepare and characterize nanocomposite films to improve the treatment of skin wounds by applying the film as a bandage. To modify chitosan (Cs) and to prepare nanocomposites, a mixture between titanium dioxide nanoparticles (TiO 2 NPs) was performed at different concentrations (2, 5, 10 and 15 wt%) and oleic acid (OA). The thin nanocomposite films were prepared by using casting method. The prepared films (Cs, Cs/TiO 2 NPs, Cs/OA and Cs/OA/TiO 2 NPs) were described by water absorption (swelling study) and biological degradation. Physico-chemical characterizations of Cs, Cs/OA, Cs/TiO 2 NPs and Cs/OA/TiO 2 NPs (with only 15 wt% TiO 2 NPs) films were determined by X-ray diffraction, transmission high-resolution electron microscopy, field emission scanning electron microscopy, thermal analysis and Fourier transform infrared spectroscopy as well as their mechanical properties. Antimicrobial activity against microorganisms has been studied to assess activity against bacteria. The prepared nanocomposite films showed good antimicrobial activity for both Gram-positive and Gram-negative bacteria. The therapeutic effects of Cs-TiO 2 NPs-oleic acid nanocomposites on healing excision wounds were studied in rat animal model. The data obtained revealed that groups treated with nanocomposites showed enhancement wound closure and speed up wound healing time. K E Y W O R D S antimicrobial activity, chitosan and oleic acid, chitosan and titanium dioxide nanoparticles, nanocomposites films, wound healing 1 | INTRODUCTION Bionanocomposites are beneficial and have been used in a wide range of applications in many fields such as physical, biological, biomedical and pharmaceutical applications (Díez-Pascual, 2019; Loureiro, Azoia, Gomes, & Cavaco-Paulo, 2016; Nikalje, 2015). Nanoparticles are an important component of many classes of biopolymers and bionanocomposites (Lenart & Hore, 2018). Numerous research has stated that TiO 2 nanoparticles at a low content (1-5%) may improve the physical-thermal properties of biocomposite films (Oleyaei, Almasi, Ghanbarzadeh, & Moayedi, 2016; Zhang et al., 2017). Khan and his colleagues reviewed a detailed overview of the properties, and applications of nanoparticles (NPs) present in various forms (Khan, Saeed, & Khan, 2019). Wound dressings develop according to the cause of different wounds. Various types of wound dressings, for example, xerogels, charcoal, alginate, chitosan, and hydrogel, have been introduced for this purpose (Abbasalipour, Mirjalili, Khajavi, & Majidi, 2014).