The transient freezing/solidification of water subjected to shear flow inside a rectangular cell is investigated under laminar flow conditions. A flow of freezing water is established inside the cell by cooling the top surface of the conductive, copper plate that forms the cell’s top side by contact with boiling liquid nitrogen (C). This heat removal results in an ice layer that forms and grows gradually on the ceiling of the cell, which is subjected to shear from the flow below it inside the channel. The spatiotemporal characteristics of the ice layer are recorded with optical, laser-based measurements and are compared with predictions from a transient freezing model that is developed for this purpose. Furthermore, tracer particles are introduced into the flow to aid the tracking of the ice layer and to allow for measurements based on particle image velocimetry (PIV) of the velocity field inside the flow during the ice-layer evolution. After an initial time-lag/‘buffer’ period (of s) that depends on the flow conditions, a quasi-linear growth of the ice layer is observed; at longer times the thickness of the ice layer reaches a maximum and then decreases again. The increase in the thickness, and hence thermal resistance, of the ice layer is counter-balanced by a decrease in the temperature of the copper plate and, therefore, a decrease in the temperature difference across the ice layer. Furthermore, it is found that the flow is associated with symmetric velocity profiles, recorded along the vertical spanwise length between the ice layer at the top of the cell and the floor of the cell, while an increase of the velocity maxima is recorded as the ice layer gradually thickens and, consequently, the flow cross-section is reduced. A constant heat flux of 19.7 × 103 W m is measured on the top side of the channel, while the heat transfer coefficient on the top side of the channel is found to be in the range of 90–110 W m K depending on the wall temperature. Finally, from comparisons against the experimental data, it is concluded that the model developed herein is able to predict the freezing of water and the growth of the ice layer in these flows over a range of water inlet temperatures and Reynolds numbers. This model can be incorporated in thermohydraulic codes for the design of relevant heat-exchange components in the precence of freezing/solidification.