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 this 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.