The workshop Combinatorics on words (and related topics) is an informal continuation of the successful and productive series of meetings Cˇ esko-Slovenská Mela, held annually at the end of September from 2012 - 2015 in Telcˇ . The workshop is a meeting of researchers and students working primarily in the areas of Data compression. It is intended to be a meeting place for different working groups mostly from the Czech Republic and Slovakia, but an invitation to participate was extended to colleagues outside these two countries, therefore the language of the meeting is English. Presentations and papers for the workshop were solicited. All papers submitted were reviewed by two independent reviewers. The format of the workshop consists of sections where new results and work in progress are presented, as well as sections (and that is the main focus of our meeting) where open problems and common projects are discussed, proposed, and worked on. The organizers of the workshop are grateful to the organizing and program committees of ITAT for the chance to renew the series of conferences within the frame of ITAT and for all their help.