  This volume contains the post-proceedings of the Twelfth International
Workshop on Graph Computation Models (GCM 2021). The workshop was part of STAF
2021 (Software Technologies: Applications and Foundations) as an
online-workshop on 22nd June 2021.
  Graphs are common mathematical structures that are visual and intuitive. They
constitute a natural and seamless way for system modelling in science,
engineering and beyond, including computer science, biology, business process
modelling, etc. Graph computation models constitute a class of very high-level
models where graphs are first-class citizens. The aim of the International GCM
Workshop series is to bring together researchers interested in all aspects of
computation models based on graphs and graph transformation. It promotes the
cross-fertilizing exchange of ideas and experiences among senior and young
researchers from the different communities interested in the foundations,
applications, and implementations of graph computation models and related
areas.
