Donald James DePaolo (born 1951) is an American professor of geochemistry in the department of earth and planetary science at the University of California, Berkeley and associate laboratory director for energy and environmental sciences at the Lawrence Berkeley National Laboratory.

DePaolo and his then advisor Gerald Wasserburg made the first Nd isotope measurements on terrestrial igneous rocks.

An important byproduct of this work was the development of epsilon notation (ε), with which initial 143Nd/144Nd values could be distinguished from the chondritic uniform reservoir (CHUR) in parts per ten thousand.

DePaolo's work has since led to significant advances in using various isotope systems to constrain rates of metamorphic processes [6], quantify continental weathering and elemental seawater budgets through geologic time and model fluid-rock interactions.

As principal investigator of the Hawaii Scientific Drilling Project (HSDP), DePaolo and coworkers sampled the flank of Mauna Kea volcano to a depth of several kilometers.