Although compact separation by a hydrocyclone is popular in the chemical and petro-chemical industry, the separation of dissolved gas from continuous liquid in a hydrocyclone is rarely mentioned, and few investigations consider the gas solubility changes occurring with the cyclone flow. This work investigates dissolved carbon dioxide separation from water by an inner cone hydrocyclone. When the inlet mass flow is less than 1.2 m(3)/h, increasing the inlet mass flow could increase the separation efficiency. When the inlet mass flow is more than 1.2 m(3)/h, increasing the inlet mass flow will decrease the separation efficiency. An optimum inlet mass flow of 1.2 m(3)/h can provide the maximum separation efficiency of 40.2%. Turbulence simulations also assist in analyzing the flow pattern and the separation progress. (C) 2016 Published by Elsevier B.V.