Due to its good processability, oil and heat resistance, polyamide (PA) plays a key role in the engineering plastics market, with the third-highest share of 14.3 % [1]. However, several drawbacks, such as high moisture absorption and poor dimensional stability, limit the application of PA. Due to its dimensional stability, water and temperature resistance, poly (2,6-dimethyl-1,4-phenylene ether) (PPE) is a promising blend partner to overcome the mentioned drawbacks of PA. As both polymers are immiscible when blended, compatibilization is needed to improve the interfacial interaction, thus mechanical properties [2]. Poly (styrene-co-maleic anhydride) (SMA) is commonly used for PA6/PPE blends [3], in which its type, concentration and the mixing protocol effects the compatibilization quality. [4] Nevertheless, a fundamental understanding on the influence SMA solubility in PPE on blend morphology and mechanical properties of PA66/PPE blends is still missing in literature. In this study, we report the effect of the mixing protocol and SMA type on the morphology of immiscible PA66/PPE blends, melt-blended with a twin-screw extruder. One- and two-step mixing protocols were applied for different SMAs having maleic anhydride (MA) contents of 4, 8 and 25 wt.-%. The SMA concentration was kept constant at 10 wt.-% in PA66/PPE ((50/50) w/w). Compared to one-step mixing, the tensile strength (σm) and elongation at break (εb) increased up to 35 % and 50 %, respectively. Furthermore, we achieved a maximum σm of 77 MPa and εb of 4.0 % with a two-step processing and droplet-sea morphology for 8 wt.-% MA, where PPE has a bimodal distribution in PA66. References: [1] World plastic production 1950 – 2015, https://committee.iso.org/, Accessed: 07/08/2019. [2] Koning, Duin, Pagnoulle & Jerome. Prog. Polym. Sci. 23, 707–757 (1998). [3] Guo, Z., Shen, Y. & Fang, Z. J. Polym. Eng. 34, 193–199 (2014). [4] Chang, F.-C. & Hwu, Y.-C. Polym. Eng. Sci. 31, 1509–1519 (1991). Keywords: Polyamide 66 (PA66); poly (2,6-dimethyl-1,4-phenylene ether) (PPE), compatibilization; Styrene-maleic anhydride copolymer (SMA); blend; morphology; processing