In this work have been evaluated adhesion of coconut and banana fibers on several treatment conditions and using two polymeric matrix. Fibers were extracted from banana pseudostem and coconut esocarp, which were dried at a temperature of 40°C and 90°C, determining how the drying temperature influences the mechanical properties. Choosing 40°C for banana fibers and 90°C for coconut fibers as the best temperature, these sets of fibers were treated with alkali and various properties were compared using characterization techniques such as tension tests, scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). Simply dried and INFORME FINAL DEL TRABAJO DE INVESTIGACIÓN CONVENCIONAL Comité de Acreditación y Currículo Facultad de Ingenierías por una universidad con calidad, moderna e incluyente Carrera 6ª. No. 76-103 Montería NIT. 891080031-3 - Teléfono: 7860300 - 7860920 www.unicordoba.edu.co mercerized fibers were embedded in polymeric matrices to determine the influence of fiber treatment on adhesion with polylactic acid (PLA) and unsaturated polyester resin and to obtain manufacturing parameters to improve the properties of natural fiber-reinforced composites using 3D printing and resin transfer molding (RTM) processes. Using the PullOut fiber extraction test, it was possible to prove that mercerizing improves the interfacial adhesion with the abovementioned matrices.