Samples from Thai manuscripts and banner paintings dated from the late 17th to the early 20th centuries were analyzed by X-ray fluorescence, scanning electron microscopy, X-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy to determine the materials used. This revealed a chronological change in palette with the introduction of imported pigments in the later 19th and 20th centuries. In the late 17th and 18th centuries, the main green used on the manuscripts was an organic copper salt with malachite used on the banner paintings and on only one manuscript. Both the organic copper salt and malachite were replaced by emerald green and mixtures of Prussian blue plus gamboges on both manuscripts and banner paintings and of Prussian blue with chrome yellow or zinc yellow (zinc potassium chromate) on some manuscripts. Similarly, indigo in the late 17th and 18th century manuscripts and banner paintings was replaced by Prussian blue and then synthetic ultramarine in the 19th century. Chrome yellow was used in addition to gamboges in one later 19th century manuscript. The organic copper salt used in the 18th century was identified as a copper citrate phase. This has not been identified previously as an artist’s material although its use has been postulated based on historic texts. Copper citrate was synthesized to provide reference material for comparison with the phase found in the Thai manuscripts. The color of these synthesized copper citrates varies from deep blue-green to light blue depending on hydration. The most hydrated form is closest in color but is not identical to the deep green phase found on the Thai manuscripts. Lead white was the main white pigment in all but one manuscript, which contained huntite, a magnesium calcium carbonate. Huntite also occurred in mixtures with other pigments in two other manuscripts. In all the works studied, red lead, vermilion and red earths were used for red, orange and pink shades and red earth used in brown areas.