A series of water soluble, surface‐active ionic liquids (SAILs), namely, 1‐alkyl‐3‐methyl imidazolium chlorides ([Cn‐mim]Cl) and their mixtures with palmitic acid (PA) are investigated in Langmuir monolayers and Langmuir–Blodgett films. It is inferred from the surface pressure‐area isotherms that C16‐mim‐IL mixes non‐ideally with PA and stabilizes the binary mixed films. In addition, the residence of mim‐IL at the water surface is enhanced as a function of the increasing alkyl side chain length. Generally, the compressional moduli values decrease upon increasing the content of the mim‐ILs over a wide range of compositions. Furthermore, film relaxation measurements indicate that the IL component is selectively excluded from the mixed films upon achieving a certain target pressure. Brewster angle microscope images demonstrate minimal changes on the PA domains in the presence of either C4‐ and C8‐mim‐ILs, whereas presence of the hexadecyl counterpart results in the formation of condensed sheets. Atomic force microscopy imaging of deposited films show the formation of propeller‐like aggregates when C8‐ or C16‐mim‐IL is present in the mixed films.