The effect of temperature upon the electrochemical stripping performance of a heavy metal sensor based on carbon nanoparticles is studied. The morphological changes of the sensing surface during the multidetection of Cd²⁺, Pb²⁺, Cu²⁺ and Hg²⁺ ions are studied by TEM and SEM. The effect of the temperature on the heavy metal deposition using carbon nanoparticle-based SPEs is also compared to a sensor that does not contain carbon nanoparticles. The effect of temperature seems to be more pronounced for the nanoparticle-based sensor. This phenomenon is clarified by the electrochemical response as well as the TEM and SEM images of the sensing materials used. In addition, the response performance of the nanoparticle-based sensors for increasing concentrations of heavy metals from 5–100 μg L⁻¹ for Cd²⁺, Pb²⁺ and Cu²⁺ and from 1 to 10 μg L⁻¹ for Hg²⁺, in both single and multiple detections with potential for real applications, is presented. The nanoparticle-based sensor seems to be stable for up to one month while being used in continuous monitoring of heavy metals in seawater.