This paper reports on an experimental study of heat transfer from a heated flat plate to water flowing in rivulets. A visual study of rivulet Row has been carried out, while simultaneously making thermal measurements. We observed various flow regimes associated with small rivulets, wide flat rivulets and film Row, which were dependent on the liquid flow rate and on the way water was brought onto the plate. The measurements showed that the transitions among the different Bow regimes were accompanied by changes in the heat transfer rates.