Hydrate formation is a major concern in the oil and gas industry due to the risk that the accumulation of solids poses to the blockage of pipelines. At high pressure and low temperature conditions, a hydrate forms as a thin solid film at the interface of water and a phase containing a hydrate-forming substance, for example methane, ethane or carbon dioxide. This process is accompanied by heat release due to the exothermic nature of hydrate formation. In this study, we investigate experimentally the role of heat transfer on the lateral growth of hydrate films over the interface of sessile water drops submerged in liquid cyclopentane at sub-zero temperatures. Each drop was introduced into cyclopentane at ambient temperature using a syringe pump. The spatiotemporal variations of temperature around the drop in the bulk cyclopentane phase were measured with one-colour planar laser-induced fluorescence (1-c PLIF), using a temperature-sensitive fluorescent hydrophobic dye, Nile Red, dissolved at a concentration of 1.7×10^-6 mol/L. High-speed backlight imaging was employed to observe macroscopically the transformations in the morphology of the hydrates over a range of bulk cyclopentane temperatures from −7.5 °C to 0.3 °C, with the appropriate subcooling temperature varied accordingly between 15.2 °C and 7.4 °C. It is revealed that a decrease in the bulk cyclopentane temperature resulted in morphological changes in the appearance of the hydrate film, from dendritic to spherulitic structures. When convection is limited, as in the present experiments, the presence of hydrates can result in elevated temperatures near the drop interface, thus suggesting the possibility of detection of the latent heat release using the 1-c PLIF method.