[en] This paper summarizes the activity performed for assessing the capabilities of RELAP5/Mod3.3 and TRACE5.0 codes at supercritical pressure conditions in heated channels. The study, conducted in the framework of the IAEA CRP 'Heat Transfer Behaviour and Thermo-Hydraulics Code Testing for SCWRs'., includes two main activities. The former is related with the implementation into the sources codes of the correlation of Mokry et Al., developed for supercritical water in vertical channel. The achieved results have been compared with the experimental data from Task no. 9 of IAEA CRP benchmark. The second activity aims to assess the behaviour of the two codes in the prediction of the stability conditions in heated channels with water at supercritical pressure in vertical and horizontal channel. The dimensionless numbers, introduced by Ambrosini [Ambrosini 2009], have been used to present the results and to identify the instability map regions. (author)