Food 3D Printing is a novel technology which allows manufacturing three dimensional edible objects with customized shape and structure, by extruding and depositing progressively several layers. The overall process is complex since many phenomena occurs simultaneously: non-Newtonian flows, heat transfer, sintering between different layers and solidification of the printed material after deposition. This study focuses on the interplay between the rheological and thermal properties of chocolate products, and printing conditions, in order to predict the stability of 3D printed structures. The effect of printing velocity (Vp) and environmental temperature (Te) on chocolate printed structure was investigated using IR thermography to characterize the local cooling dynamics.3D edible structures can be manufactured successfully only below a critical print velocity which depends on the environmental temperature. At Te=18°C, Vp should be lower than 16 mm/s while at 20 °C lower than 8 mm/s. This conditions ensure a sufficient cooling and solidification of the cocoa butter, which is needed for print stability. A stability criterion based on the local yield stress is proposed to explain the stability or collapse of the 3D printed structures. The understanding provided by this work can help optimising food 3D printing conditions and product formulation. •IR Thermography is used to characterize quantitatively the temperature of 3D printed food..•A strong change in rheology, due to cooling, after deposition ensures stability.•Room temperature strongly affects heat transfer dynamics and print stability.•Lower printing velocity allows printing structures at higher room temperature.