The pump responsible for gastric acid secretion is

Gastric parietal cells are highly specialized for their unusual task of secreting concentrated acid. The cells are packed with mitochondria that supply energy to drive the apical H+,K+-ATPase, or proton pump, that moves H+ ions out of the parietal cell against a concentration gradient. The apical membrane also contains potassium channels, which supply the K+ ions to be exchanged for H+, and Cl- channels that supply the counterion for HCl secretion.