The focus of Hieberts research was the history and philosophy of chemistry and physical sciences in the 2nd half of 19th century and 1st half of the 20th century. During his lifetime he completed three books and his fourth book (which deals with acoustics) was nearly complete at the time of his death. His book 1961 book The Impact of Atomic Energy examined the Manhattan Project, the atomic bombs dropped on Hiroshima and Nagasaki, and WW IIs consequences related to atomic energy from an ethical and religious perspective. He wrote numerous papers on the history of science, the relations between science and religion, and the philosophy of science as viewed by outstanding scientists of the modern era, especially among those scientists from 1850 to 1930 in Germany and Austria. His 1962 book Historical Roots of the Principle of Conservation of Energy is a notable achievement in writing the history of thermodynamics. He wrote papers about the science and philosophy of Max Planck, Ernst Mach, Walther Nernst, Ludwig Boltzmann, Hermann von Helmholtz, and Wilhelm Ostwald. Hiebert 
had a strong conviction that historians of science should have a good, scientific grounding in the particular science that they study and write about.