The use of quaternary ammonium salts (Quats) as phase-transfer catalysts is analyzed from a technological and economic point of view. The limiting price for Quats is determined by establishing a qualitative relationship between technical parameters and economic factors. Specific examples show that the present price of Quats limits their commercial use to the area of high-priced commodities and specialty chemicals. Quats may be used i commodity manufacture provided they are produced on a larger scale. A simulation of such a large-scale production of a representative Quat (tetrabutylammonium bromide) has been made and its consequences are discussed.