A new instrumentation for in situ X-ray powder diffraction allows to follow structural changes in the crystal structure of flexible coordination polymers during adsorption and desorption of gases. The system is based on closed cycle He-cryostat that ensures the high temperature stability in the range of 5.5-450 K. The automated gas dosing system facilitates the physisorption measurements in the pressure range of 0.01-130 kPa. The system is implemented on KMC-2 and MAGS beamlines at Helmholtz Zentrum Berlin für Materialien und Energie. Using new instrumentation, the adsorption of CO₂ and n-butane at 273 K on a flexible two-dimensional coordination polymer ELM-11 (ELM - Elastic Layer Material) was investigated.