In the battery industry, the term "depolarizer" has been used to denote a substance used in a primary cell to prevent buildup of hydrogen gas bubbles.
The term "depolarizer" can be considered as outdated or misleading, since it is based on the concept of "polarization" which is hardly realistic in many cases[citation needed].
If such a layer of hydrogen or even H2 gas bubbles appear on the positive plate of a battery, they interfere with the chemical action of the cell.
Polarization in galvanic cells causes the voltage and thus current to be reduced, especially if the bubbles cover a large fraction of a plate.
Examples include: Nitric and chromic acids are powerful oxidizing agents, and effective depolarizers, but their hazardous nature makes them unsuitable for general use.