Abstract: A nanoscale temperature detector including a diamond sensing probe with a transverse dimension of at least 200 nanometres and a sensing tip-having a curvature radius of less than 100 nanometres, less than 10 nanometres or less than 1 nanometre, and a plurality of colour centres, whose emission count rate show temperature-sensitive features. The diamond sensing probe has a transverse dimension of at least 200 nanometres and is connected to a to a detector system by means of a mounting structure. A thermal isolation barrier thermally decouples the sensing probe from the detector system.