Alkaline batteries are a type of power cell dependent upon the reaction between zinc and manganese dioxide (Zn/MnO2).

Compared with original zinc-carbon batteries, while both produce approximately 1.5 volts per cell, alkaline batteries have a higher energy density and longer shelf-life.

Compared with silver-oxide batteries, which alkalines commonly compete against in button cells, they have lower energy density and shorter lifetimes.

The alkaline battery gets its name because it has an alkaline electrolyte of potassium hydroxide, as opposed to the acidic electrolyte of the zinc-carbon batteries which are offered in the same nominal voltages and physical size.

The amount of current an alkaline battery can deliver is roughly proportional to its physical size. This is a result of decreasing internal resistance as the internal surface area of the cell increases. A general rule of thumb is that an AA alkaline battery can deliver 1000mA without any significant heating. Larger cells, such as C and D cells, can deliver more current. Applications requiring high currents of several amps, such as high powered flashlights and boom-boxes, will require D sized cells to handle the increased load. Volume for volume, alkaline batteries have inferior current handling capacity when compared to other chemistries like NiCd and NiMH. However, alkaline batteries cost significantly less.

Over time, alkaline batteries are prone to leaking potassium hydroxide, a caustic agent that can cause respiratory, eye and skin irritation. This can be avoided by not mixing different battery types in the same device, replacing all of the batteries at the same time, storing in a dry place, and removing batteries from devices for storage.