Abstract: The invention relates to particles for determining the local temperature in organic and non-organic bodies. The temperature is determined using nuclear magnetic resonance spectroscopy (NMR) when the particles are utilized. The aim of the invention is to provide temperature sensors which allow the temperature to be measured in vivo in a contactless manner on a nanometer scale while making it possible to use NMR-active substances which are foreign to the body or are contained therein in small quantities only and can be toxic, the temperature sensors allowing the temperature to be measured in vivo also on materials that are foreign to the body, e.g. nanoparticles that are heated in the body in a certain way. Another aim of the invention is to produce the temperature sensors with defined geometrical dimensions in the nanometer range.