Acanthophyllum laxiusculum is one of the most widely distributed species of the genus in Iran that flourishes in steppe and mountainous regions of the country. In the present study, water-soluble content of A. laxiusculum roots was extracted by boiling water and further successively purified partially by a defined solvent system. Surface tension measurements revealed the ability of plant extract to decrease the surface tension of water from 72 to 38mN/m with a critical micelle concentration (CMC) of 87.3 mg/l. The partially purified natural extract (PPNE) exhibited 65% emulsification activity (E24) on kerosene. A combination of UV–VIS spectroscopy and Fourier transform infrared spectroscopy (FTIR) demonstrated the presence of saponin compounds in PPNE. Moreover, thermostability of PPNE was evaluated by thermal gravimetric analysis (TG) and differential thermal analysis (DTA). TG-DTG analysis showed a complex three-stage thermal degradation mechanism and this conclusion was also supported by the DTA spectrum.