The RSCVn system \sigma Geminorum was observed by XMM-Newton on April 2001 during a large flare .
We model the emission measure distribution ( EMD ) during the flare and during a quiescence period .
In the flare , a two phase behaviour is found in which the cool plasma ( kT < 2 keV ) is not disturbed while a large hot component , at temperatues of kT > 3 keV emerges .
Fundamental limitations on EMD modeling of high temperature plasmas are then discussed , in the context of the \sigma Geminorum flare .