Dear colleagues, We would like to remind you that the *XVI Portuguese Category Seminar* will take place at the Centre for Mathematics of the University of Coimbra, Portugal, on *12–14 November 2026*. We warmly welcome contributions on category theory and its connections with algebra, topology, logic, and computer science. *Participation is free of charge*, and the key deadlines are as follows: - *Abstract submission:* 29 October 2026 - *Notification of acceptance:* by 3 November 2026 - *Registration:* 5 November 2026 Both the abstract submission and registration deadlines are at 23:59 (Coimbra time). Registration is required for all participants, including those who do not intend to give a talk. The registration form, abstract template, and further details are available on the seminar website: https://flnlucatelli.github.io/2026/pcs.html *How to register and submit an abstract* All participants should register by sending an email to *Maria Manuel Clementino* (mmc@mat.uc.pt), with the subject line *PCS-2026 SUBMISSION*. The submission procedure depends on whether you intend to give a talk: 1. *If you wish to propose a talk:* Complete the registration form available on the seminar website and paste it into the body of your email. Attach your abstract in two formats: the *LaTeX source file (.tex)*, prepared using the template provided on the website, and the *compiled PDF (.pdf)*. Please submit both the registration form and the abstract by *29 October 2026*. 2. *If you wish to attend without giving a talk:* Complete the registration form available on the seminar website and paste it into the body of your email. No abstract or attachments are required. Please register by *5 November 2026*. There is no separate online submission system. *All registrations and talk proposals should be sent by email*, following the instructions above. We would be grateful if you could circulate this announcement among colleagues, researchers, and students who may be interested. We look forward to welcoming you to Coimbra and to another stimulating gathering of the category theory community. Best regards, *Fernando Lucatelli Nunes* On behalf of the Organising Committee