This paper describes research carried out in order to determine the techniques that the Mexicas used to create the wall paintings at the Great Temple of Tenochtitlan in Mexico City. After excavations started in 1978, the paintings on mud and on lime plaster were the focus of an extensive study, which included the identification of the components. The painting technique, however, was not completely identified. Some other issues, such as the composition of the blue pigment, also required further study. This new research project included the creation of synthetic samples and the analysis of samples employing diverse techniques of analysis: optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, infrared spectroscopy, Raman microscopy, UV visible reflectance spectroscopy, gas chromatography-mass spectromentry, high pressure liquid chromatography, and X-ray diffraction. The research demonstrated that more than one painting technique was employed for the wall paintings. The blue pigment was identified as Maya blue due to the detection of indigo, palygorskite, and kaolinite. -- MCI