The main objective of this research is to investigate the concrete cover thickness effect on the corrosion degree of the longitudinal reinforcing steel of short circular high-performance concrete columns. The practical program consists of casting and testing six circular columns with dimensions of (150 × 1000) mm tested under a central load. Three of them were reference columns, and three were corroded using an accelerated corrosion cell. The main variable adopted in the present research included the concrete cover thickness (10, 20, and 30) mm to compare results for weight and surface area loss of corroded steel and bearing capacity reduction among all samples. The results showed that increasing the concrete cover thickness from 10 to 20 and 30 mm decreased the loss percentage of the reinforcing steel weight by (12.47, 11.82, and 11.26) %, respectively. Also, the loss percentage of the cross-sectional area of the reinforcing steel decreased by (77.44, 64.00, and 57.75) %, respectively. While bearing capacity was reduced by (29.07, 25.25, and 32.23) % for 10, 20, and 30 mm clear covers, respectively, compared with the control columns of 10, 20, and 30 mm clear covers.