Subcritical Water Extraction (SWE) operates below the critical point of water (374 deg C and 221 bar) and takes advantage of the variation in polarity of water with change in temperatre at relatively low pressure. With Subcritical Water there is also enhancement of other properties such as viscosity, surface tension, diffusion coefficient and solubility.

The tunable polarity of subcritical water (sbW) means that a particular compound can be extracted based on elevating the sbW temperature to attain the required polarity.