In this article, a hydrolyzed EVA copolymer (EVA-h) was chosen as an interfacial agent of PA12/EVA blends. The effect of EVA-h addition (5 and 10 wt% in relation to EVA phase) on morphological, interfacial and mechanical properties of the systems was investigated. The polymer blends were melt processed in an interpenetrating co-rotating twin-screen extruder. The EVA-h practically did not change the continuity index of the blends. However, it resulted in the reduction of the size of the dispersed EVA phase in polyamide. EVA-h contributed to the reduction of the interfacial tension (4.6 - 0.32 mN/m) and the formation of a stable morphology. The EVA-h improved the interaction between PA12 and EVA phases, being its effect more pronounced on the elastic modulus and hardness properties. The behavior of the mechanical properties confirmed the compatibilizer effect EVA-h in the blends. POLYM. ENG. SCI., 58:335-344, 2018. (c) 2017 Society of Plastics Engineers