The three-volume set LNCS 12181, 12182, and 12183 constitutes the refereed proceedings of the Human Computer Interaction thematic area of the 22nd International Conference on Human-Computer Interaction, HCII 2020, which took place in Copenhagen, Denmark, in July 2020.* A total of 1439 papers and 238 posters have been accepted for publication in the HCII 2020 proceedings from a total of 6326 submissions. The 145 papers included in these HCI 2020 proceedings were organized in topical sections as follows: Part I: design theory, methods and practice in HCI; understanding users; usability, user experience and quality; and images, visualization and aesthetics in HCI. Part II: gesture-based interaction; speech, voice, conversation and emotions; multimodal interaction; and human robot interaction. Part III: HCI for well-being and Eudaimonia; learning, culture and creativity; human values, ethics, transparency and trust; and HCI in complex environments. *The conference was held virtually due to the COVID-19 pandemic.