This paper proposes a hybrid dynamic model of active chilled beam (ACB) terminal unit. The model encapsulates mechanical and thermal aspects of the confined air jet and the cooling coil contained in the terminal unit and could be divided into two sub-models respectively. The models for the primary air, secondary air and mixing of them are together taken as the confined air jet sub-model. Another sub-model is the heat transfer description of the cooling coil. The model is kept simple and practical, avoiding sophisticated jet flow theories as well as heat transfer theories. Thus, in deriving the model using first principles and estimating it experimentally, a reasonable compromise is made between capturing exact underlying physics and suitability for engineering applications. Supported by experimental results from a pilot plant, unknown model parameters are identified by either a linear or nonlinear least-squares method. It is shown that static and dynamic performances of the model are satisfied, which reflect the effectiveness of this hybrid modeling technique as well. The model developed in this work is expected to have wide control and optimization applications. (C) 2014 Elsevier Ltd. All rights reserved.