This conference proceeding LNCS 12796 constitutes the thoroughly refereed proceedings of the 2nd International Conference on Design, Operation and Evaluation of Mobile Communications, MOBILE 2021 which was held as part of the 23rd HCI International Conference, HCII 2021 as a virtual event, due to COVID-19, in July 2021.

The total of 1276 papers and 241 posters included in the 39 HCII 2021 proceedings volumes were carefully reviewed and selected from 5222 submissions.

MOBILE 2021 includes a total of 27 papers; they were organized in topical sections named:

Designing, Developing and Evaluating Mobile Interaction Systems and User Experience, Acceptance and Impact of Mobile Communications.