Despite the fact that Kees van Dongen was one of the most famous painters of the twentieth century, only little information about his palette and his technique is available. To contribute to the characterization of van Dongen’s painting materials, La Violoniste, painted by the artist around 1922, has been analyzed by using three complementary techniques: macro X-ray fluorescence (MA-XRF), Raman spectroscopy and hyperspectral imaging. The elemental repartition given by MA-XRF and the results obtained thanks to Raman spectroscopy help us to complete the identification of pigments contained in La Violoniste (lead white, iron oxides, cadmium yellow, vermilion, Prussian blue, titanium white, ultramarine, a red lake, a chromium pigment and carbon black) while the results obtained via hyperspectral imaging reveal a hidden woman portrait. Besides the fact that Kees van Dongen was particularly renowned for his female portraits, this hidden composition presents stylistic similarities with the well-known portraits produced by the artist from around 1920, when he was a famous worldly portraitist. Thanks to Raman spectroscopy, visual examination and MA-XRF, we show that the original background contains ultramarine, the hidden portrait’s clothes are maybe made of the same colour as the present violinist’s dress and her face contains zinc, contrary to the violinist’s flesh which is mainly made of lead white.