  Interplanetary Coronal Mass Ejections (ICMEs) and High Speed Streams (HSSs)
are noteworthy drivers of disturbance of interplanetary space. Interaction
between them can cause several phenomena, such as; generation of waves,
enhanced geo-effectiveness, particle acceleration, etc. However, how does
thermodynamic properties vary during the ICME-HSS interaction remain an open
problem. In this study, we investigated the polytropic behavior of plasma
during an ICME-HSS interaction observed by STEREO and Wind spacecraft. We find
that the ICME observed by the STEREO-A has polytropic index $\alpha = 1.0$,
i.e., exhibiting isothermal process. Moreover, Wind spacecraft observed the HSS
region, non-interacting ICME, and ICME-HSS interaction region. During each
regions we found $\alpha$=1.8, $\alpha$=0.7, and $\alpha$=2.5, respectively. It
implies that the HSS region exhibits a nearly adiabatic behaviour, ICME region
is closely isothermal, and the ICME-HSS interaction region exhibits
super-adiabatic behaviour. The insufficient expansion of the ICME due to the
interaction with HSS triggers the system for heating and cooling mechanisms
which dependent on the degrees of freedom of plasma components.
