The colour thickness, hardeness and roughness of samples of the pictorial layers of Roman mural paintings from the Acropolis of Lero (Alpes-Maritimes, France) were studied. The average and surface composition of the paint layers and of the intonaco were also determined by means of electron microprobe analysis and x-ray diffraction. The materials used seem to conform with Vitruvius specifications except for the use of pure heamatite instead of red ochre and the systematic addition of clay wherever the pigment does not contain any. Roughness and texture of the material seem to be linked the practice of a non-abrasive polishing of some paint layers. References, tables and diagrams.