Hypothesis: The molecular hydrogen-bonding process in liquids with relatively small molecules, like butan-1,4-diol (BDO), results in interesting molecular-aggregation phenomena. These are reflected in a supramolecular self-assembly type of structure that is also expected to importantly influence the rheological properties of the system. The combination of experimental and theoretical methods should be able to reveal such influences in the important feedstock chemical BDO at low and moderate temperatures and further provide an application of the verified BDO model for a theoretical study of the structure at higher temperatures, for which serious health hazards make extensive experimental studies difficult. Experiments: BDO was studied in the temperature range between 25 and 225 degrees C utilizing the experimental small- and wide-angle x-ray scattering method, molecular dynamics simulations, and the 'complemented-system approach'. Findings: The theoretical results were experimentally verified and revealed important novel temperature-dependent structure and viscosity-related information, e.g., on aggregate sizes and self-diffusion coefficients, that would remain hidden in purely experimental studies. BDO has diverse applicability in many fields of research and industry, where it is often exposed to high temperatures. Using an experimentally verified model we were able to calculate reliable viscosity and self-diffusion coefficient values for the BDO molecules under such conditions. (C) 2019 Elsevier Inc. All rights reserved.