The ninth edition of the Workshop on New Trends in Quaternions and Octonions - NTQO 2025 aims to present and discuss recent developments in the fields of quaternions and octonions, bringing together scientists from pure and applied mathematics, physics, scientific computing, engineering, and other related disciplines.

The 2025 workshop is especially significant as it commemorates the 75th birthday of Professor Helmuth Malonek, one of the founders of the NTQO workshop series. Furthermore, we also intend to celebrate the 145th anniversary of the birth and the 75th anniversary of the passing of Rudolf Fueter, a historical figure in the field of quaternions.

The workshop will take place at the University of Aveiro, on September 12-13, and will count on invited lectures and short communications. It will be held in a hybrid format to accomodate participants who may be unable to attend NTQO 2025 in person.

The event is jointly organized by the the Center for Research and Development in Mathematics of the University of Aveiro (CIDMA-UA), the Center of Mathematics of the University of Minho (CMAT-UMinho), and the Center of Mathematics and Applications of the University of Beira Interior (CMA-UBI). It also has the support of the International Center for Mathematics (CIM).