The spreading behavior of poly(2-acrylamidohexadecylsulfonic acid-co-styrene) (PAMC16SSt) random co-polymers with various compositions was investigated by measurements of the surface pressure-area (pi-A) isotherms. The random copolymers formed stable condensed monolayers with a high collapse pressure (about 40 mN m-1) over a wide range of styrene contents. The collapse pressure increased somewhat with increase in the styrene content. These facts indicate that more hydrophobic units can be incorporated into a stable copolymer monolayer if 2-acrylamidohexadecylsulfonic acid is used as an amphiphilic comonomer instead of N-dodecylacrylamide. A linear relationship between the average limiting surface area per monomer unit and the styrene mole fraction was observed up to about 0.6 styrene mole fraction. The addition of CdCl2 into the water subphase had little effect on the spreading behavior of PAMC16SSt Monolayers. The transfer of PAMC16SSt was affected by the subphase and the copolymer composition. In the case of CdCl2 aqueous solution (1 mmol L-1), all the monolayers could be transferred onto a hydrophilic glass substrate by an upward stroke with a transfer ratio of unity. However, the transferred monolayers were lost in the downward stroke.