While agent-based models (ABM) are increasingly used to study overall system behaviour of various systems, they can also be hard to use by people and organisations that are not familiar with this modelling paradigm. Creating usable agent-based models is thus an important aspect to consider while constructing agent-based models. However, an ABM modelling approach that explicitly addresses usability does until this point not exist. This thesis proposes an ABM usability modelling approach, which is designed and applied for an ABM of gas desulphurization technologies that is developed in collaboration with Shell P&T. The approach is based on dividing usability for ABM into three aspects: (1) experience, (2) functionality and (3) interaction. By defining layers of usability and put them into perspective, an actionable ABM usability modelling approach is obtained. Continued use of this modelling approach would enable the development of this approach into a generic usability modelling approach. Besides future research for the usability modelling approach, future research is defined for modelling process technology in socio-technical systems using ABM.