Nanocomposite Langmuir-Blodgett films of poly(maleic monoester) (PMA)/Fe3O4 nanoparticles were prepared by transferring PMA/iron oxide nanoparticles complex monolayers in a hydrosol subphase of Fe3O4 nanoparticles onto solid substrates. A Mossbauer spectrum of the nanoparticles showed the highly crystalline nature of the magnetite structure. Homogeneous dispersion of Fe3O4 nanoparticles between poly(maleic monoester) layers was observed with transmission electron microscopy (TEM), and surface morphology of the nanocomposite film was studied with atomic force microscopy (AFM). The magnetic properties of the Fe3O4 nanoparticles and the nanocomposite Langmuir-Blodgett film of poly(maleic monoester) (PMA)/ Fe3O4 nanoparticles were studied with vibrating magnetometry (VSM) by obtaining magnetic hysteresis loops. The PMA is a polymeric surfactant and interacts with Fe3O4 nanoparticles by electrostatic attraction between carboxylate groups of PMA and the charged Fe3O4 nanoparticles. This interaction stabilizes the homogeneous dispersion of nanoparticles between the PMA polymer layers. The surface morphology, as shown by AFM images, gives well-formed surface structures that were evenly spaced by iron oxide nanoparticles. The average height of one layer of the PMA/iron oxide nanocomposite film is determined to be 12.9 nm and this is approximately consistent with the summation of the PMA thickness and the average iron oxide diameter with an average roughness of 3.3 nm. The cross sectional AFM image also shows homogeneous distinct single domains of Fe3O4 nanoparticles in the nanocomposite film.