The composition of the materials present in prehistoric paintings discovered on the walls of the Abrigo Remacha rock shelter (Villaseca, Segovia, Spain) has been characterised by micro-Raman spectroscopy. In addition, scanning electron microscopy and energy dispersive X-ray microanalysis have been used as auxiliary techniques. The results show that haematite (α-Fe2O3) is the main component of the red pigment. Amorphous carbon and paracoquimbite (Fe2(SO4)3.9H2O) have been detected in the bluish black pigment used in a significant bi-colour pictograph. This is the first time that this mineral has been discovered in a prehistoric painting. Accretions of whewellite and weddellite form crusts covering most of the painting panel. Different carbonates are the main components of the rocky substrate. The detection of gypsum on the surface of the panel is associated to the flaking process that is affecting the painting panel. Copyright © 2013 John Wiley & Sons, Ltd.