Context: Demand response is a new study area and many countries intend to create roadmaps to activate their implementations. Smart Grid Maturity Model (SGMM) defines the characteristics and targets related to customer, but it does not adequately elaborate and provide a guiding perspective for demand response. Objective: In addressing the gap mentioned, this article presents a Demand Response Process Assessment Model (DRPAM) as a fundamental proposal towards evaluating, implementing, and improving capabilities of cus-tomers' demand response processes. Method: The standard of ISO/IEC 33004 and the second maturity level of "Customer" domain in SGMM were referenced to develop the DRPAM. Literature studies and technical reports were examined to determine the key processes of the model, while Waterfall and Agile software development models and Action Workflow Loop were used to identify process practices. The set of key processes was defined, updated and verified using expert opinions gathered by Delphi study technique applied in five rounds. It was then used for an exploratory case study assessment in an organization that conducts research and development activities in this field. Results: Eight processes were identified with purpose, outcomes, base practices, work products (as inputs and outputs), and responsible roles of implementation. DRPAM is the first detailed model intended to reduce time and energy loss for demand response pilot studies of customers. The results of the case study assessment indi-cated that DRPAM was found satisfactory in identifying capabilities of demand response processes and of providing a roadmap for their improvement. As future work, the model will be validated by conducting multiple case studies.