<div class="htmlview paragraph">This paper describes the thermal balance test which has been performed on the spectrometer SPI Structural and Thermal Model (INTEGRAL project) from August 27^th to September 17^th 1999. Main SPI modes have been simulated in order to qualify the instrument thermal control.</div> <div class="htmlview paragraph">MLI efficiency has been measured, as well as thermal conductance to the payload module (PLM). For this, a specific thermal adaptator (a mechanical frame and two aluminum plates regulated by two cryostats) has been developed and will also be used for thermal vacuum tests of the SPI Flight Model. This thermal adaptator and its behavior during thermal balance test are described.</div>