Gas hydrate formation kinetics were investigated in a Kenics static mixer. When operated Under thermodynamic conditions (pressure or temperature), the hydrate formation rate increased and the HFC-134a gas bubble was covered with a hydrate "shell". This hydrate shell inhibited hydrate growth because of resistance to mass transfer. Water recycling in the hydrate reactor accelerated hydrate formation by increasing the gas-water interface during water-gas cocurrent flow and causing the continued presence of a fresh interface in the counterflow. The kinetic data indicated that the hydrate formation rate would be equal to the mass transfer rate including the rate of hydrate shedding from the gas bubble. Enriched HFC-134a gas could be continously recovered from an HFC-134a-nitrogen mixture in a continuous hydrate formation system. The hydrate formation rate constant for the mixed gas depended on the feed gas components.