MetOp is a series of three meteorology and climate monitoring satellites, which will be launched using the Russian Soyuz-Fregat vehicle over a period of 14 years starting in 2005. MetOp will form part of the American ‘Polar Orbiting Environmental Satellites’ (POES) programme, a further step in European/American collaboration in space. The MetOp satellites will fly in a sun-synchronous polar orbit at an altitude of between 800 and 850km, with a repeat cycle of 29 days. The satellite is based on the successful Spot platform, which has carried a number of European earth observation satellites over the last 15 years, and consists of two parts: 1. The Payload Module (or PLM) which carries twelve instruments, provided by the European Space Agency (ESA), the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), the American National Oceanic and Atmospheric Administration (NOAA) and the French space agency, CNES. 2. The Service Module (or SVM) which carries the housekeeping subsystems - power, propulsion, attitude control, command and control, telemetry, and thermal control.The design of the MetOp platform allows these two components to be developed, analysed and tested separately - a feature that was especially important for Envisat, and also for MetOp as these spacecraft are too large to fit comfortably inside a conventional solar simulation chamber as a single assembly. The complete MetOp satellite has external dimensions of 6.3m by 2.8m × 2.1m with all the appendages stowed.The PLM test was described at the 2003 ICES conference (Ref  and ). This paper will concentrate on the thermal balance testing of the proto-flight model (PFM) SVM, and comparisons of experiences on both modules will be made.The PFM Service Module was tested in December 2002 using a hybrid test method, combining both classic solar simulation and additional infra-red (IR) test elements. Subsequent flight models will be tested using only IR test methods.This paper discusses the measured performance of the PFM SVM thermal control system and compares it with the pre-test predictions. The correlation activities undertaken to improve the accuracy of the predictions are discussed, and the impact of the test adaptors and SVM configurations on the test results and correlation is addressed. The final thermal mathematical model shows very good correlation between predicted and measured thermal performance, and the model is therefore validated for predicting the in-flight behaviour of the MetOp satellite.