A carboxymethyl pullulan with 1.4 carboxymethyl functions per anhydroglucose unit has been esterified with bromododecane. The number of dodecyl chains per anydroglucose unit calculated from elemental analysis is 1.15 +/- 0.09. The partially esterified carboxymethyl pullulan is able to form Langmuir films. Pressure-area isotherms are reproducible, and the film is characterized by a very high stability. IR spectroscopy analysis of Langmuir-Blodgett films prepared on subphases with various DT-I confirms that the esterification was not complete. Scanning force microscopy images of a monolayer transferred onto muscovite show the great homogeneity of the monolayer. While the monolayer transferred on muscovite is fragile, multilayers transferred on CaF2 slides are resistant to mechanical and chemical treatments.