Updated project metadata. Campylobacter jejuni is one of the major causes of food-borne infections world-wide. The species is strictly host associated and tolerates mild levels of acidity and alkalinity. The ability to survive pH challenges is one of the key aspects of the ability of C. jejuni to survive in food, stomach transit and enables host gastrointestinal tract colonisation. In this study C. jejuni reference strain NCTC 11168 grown within its pH physiological normal growth range (pH 5.8, 7.0 and 8.0,  = ~0.5 h-1) and exposed to pH 4.0 shock for 2 hours. Proteins extracted from biomass were quantified using a combined data dependent and independent acquisition label-free based approach with the aim to identify pH-dependent proteins that respond in a growth phase independent manner. It was discovered that gluconate 2-dehydrogenase GdhAB, NssR-regulated globins Cgb and Ctb, cupin domain protein Cj0761, cytochrome c protein CccC (Cj0037c), and phosphate-binding transporter protein PstB all show acidic pH dependent abundance increases but are not activated by sub-lethal acid shock. Glutamate synthase (GLtBD) and the MfrABC and NapAGL respiratory complexes were induced in cells grown at pH 8.0. The response to pH stress by C. jejuni is to bolster microaerobic respiration and at pH 8.0 this is assisted by accumulation of glutamate the conversion of which could bolster fumarate respiration. Global protein abundance reduction of proteins linked to growth and survival overalls aids cellular energy conservation thus preserving a similar growth rate.