Abstract: Abrasive cleaning and decontamination methods and systems are disclosed. The methods and systems use a high pressure liquefied gas, such as carbon dioxide, which produces insignificant quantities of secondary waste. These principles of the invention exploit the properties of the relatively high triple point of CO2 in order to first pressurize it to 35,000 to 60,000 PSI from a pressurized liquid. In the pressurized state, such a fluid can be at or above room temperature, allowing for transport over long distances in a flexible high pressure hose. At a point of use, a heat exchanger may subsequently chill the liquid, so that after expansion through a small high pressure orifice, a significant fraction of the liquid is converted to solid phase crystals exiting at high velocity to effectively clean and decontaminate. For more aggressive cleaning, abrasive particles and/or small diameter solid CO2 pellets can be entrained into the high pressure CO2 slipstream.