The aim of the ESA FRM4STS project is to establish and maintain SI (Systeme Internationale) traceability of global Fiducial Reference Measurements (FRM) for satellite derived surface temperature product validation. The project includes the design and implementation of a laboratory-based comparison of the calibration processes for FRM TIR radiometers (SST, LST, IST and others), of a laboratory-based comparison to verify TIR blackbody sources, and of field inter-comparisons with pairs of FRM TIR radiometers. As part of the project several field-campaigns for TIR FRM are performed in collaboration with CEOS and the international community.