User Persona is a structured Interaction Design method for repre- senting a group of users as conceptual models in text and pictorial formats. The regular user Persona descriptions are limited for de- signing Digital Behaviour Change Interventions for Health. First, they lack the specification of behaviour change goals and target behaviours needed to design behaviour change Interventions. Sec- ond, the regular user Personas are mostly static, and they represent only the user’s current state and do not address the users’ dynamic, long-term behavioural change needs. Third, the user Persona does not help estimate the possible behavioural patterns of the users in the specific context of behaviour change, considering various determinants that influence the users’ behaviour. The current work proposes enriching the regular user Persona descriptions with the behaviour change theory. The COM-B Model (Capability, Opportu- nity, Motivation - Behaviour) and Transtheoretical Model of Change were chosen to enrich user Persona descriptions with behaviour change theory. The current study included the first expert-based evaluation of the theory-enriched Persona description with an In- teraction Design expert. The usefulness and overall approach of the enriching Persona descriptions were positively assessed, and future work on making the approach more explicit and precise is recommended