Temperature regulating system for use in fluid ejection devices, such as inkjet printing devices, are provided. Such temperature regulating systems can include an ink reservoir, a printhead and optionally an intermediate ink container. Exchange of ink between the ink reservoir, or optionally the intermediate ink container, and the printhead regulates the temperature of the printhead and makes the temperature substantially uniform from drop ejector to drop ejector. Optionally, the ink is transported in a fluid communication path that is in contact with a thermally conductive substrate to further dissipate heat. Printing devices comprising such inkjet cartridges are also provided.