Roman wall paintings at the archaeological site of Ostia Antica dating from the 1st century BCE to the 4th century CE were studied in an integrated non-invasive approach using portable instrumentation, namely: Nuclear Magnetic Resonance (NMR), Hyperspectral Imaging (HSI), X-ray fluorescence (XRF), Visible Induced Luminescence (VIL), External Reflectance Fourier-Transformed Infrared Spectroscopy (ER-FTIR), Raman and Near Infrared (NIR) Spectroscopies. The objective of this study is threefold: to investigate the materials and techniques of wall paintings at Ostia Antica in order to gain insight into the evolution of the use of materials and painting techniques over time, the testing of novel instrumentation in archaeological contexts such as portable HSI and the recently developed NMR hardware and stratigraphy protocols, as well as to aid in the conservation efforts at the site by providing information on the material composition of the walls. Some of the main results of four campaigns dating 2019-2023 are presented.