We present a theoretical and experimental study of amphiphilic particles : these are small solid spheres treated so that one part of the solid is hydrophilic whereas the other is hydrophobic. These beads have a specific behaviour at the interface between two fluids of different polarities since they are anchored at the interface along the border line between the two parts, in a large range of values for the ratio between the areas of the hydrophilic and hydrophobic sides. In addition to the intrinsic interest of the study of the wetting of mixed surfaces, these amphiphilic particles may be considered useful in technological processes such as emulsification.