In this brief review, a comprehensive collection of previous studies about geochemistry in geologic CO2 utilization and storage is presented and discussed to demonstrate the importance of CO2-rock and CO2-wellbore cement interactions in geologic CO2 utilization and storage scenarios. For CO2-rock interaction, CO2 injection reduces the pH of brine in CO2 storage reservoir, which triggers dissolution of silicate and oxide minerals in the reservoir. Dissolution of silicate and oxide minerals causes concentration increase of cations and anions, which induces secondary precipitation of silica, silicates and carbonates. For CO2-cement interaction, the interaction between CO2 and wellbore cement results in formation of a unique “sandwich” structure in cement (i.e., one carbonate precipitation zone in the middle and two dissolution zones on two sides). For both CO2-rock and CO2-cement interactions, pH plays a key role in the extent of mineral dissolution and precipitation, and the extent is dependent on pH buffering capacity of the CO2 storage reservoir. The potential of CO2-induced contaminant mobilization in deep CO2 storage reservoir and shallow aquifer is also discussed, and the chance for CO2 injection and CO2 leakage to cause severe shallow aquifer contamination is low. Cited as : Zhang, L., Wang, Y., Miao, X., Gan, M., Li, X. Geochemistry in geologic CO2 utilization and storage: A brief review. Advances in Geo-Energy Research, 2019, 3(3): 304-313, doi: 10.26804/ager.2019.03.08