The 21st edition of the European Conference on Integrated Optics (ECIO) (https://www.ecio-2019.org/ ) will take place during April 24 -26, 2019, at Ghent University, in Ghent, Belgium. The conference focuses on leading edge research on integrated optics, opto-electronics and nanophotonics and gathers experts from academia and industry to show their latest technical results, and showcase their products and services. The application scope is broad and it ranges from telecom/datacom to optical sensing applications including more disruptive areas such as quantum and neuromorphic computing. Conference topics cover waveguide technology and platforms, devices and materials, integrated circuits and applications of photonic integrated circuits (PICs). The most recent advances in photonic integration technologies, such as silicon photonics and III-V optoelectronics, is one of the main features of the conference. Assembly, packaging and hybrid integration techniques are also covered. In addition, the conference aims to discuss novel concepts on materials with unique properties such as 2D materials or phase change materials. The chairs of ECIO 2019 are Roel Baets and Gunther Roelkens, from Ghent University-imec.