Latest advances of ionic liquids (ILs) have allowed to a new application on the dissolution of calcium carbonate (CaCO3) scales where the CaCO3 scale deposition have seriously severe threat in the petroleum field. In this study, the molecular interaction between CaCO3 and ILs n-pyridinium chloride NPyCl was studied experimentally in order to get a better understanding during the dissolution of scale. NMR and FTIR spectroscopy was used to study the molecular interaction between CaCO3 and NPyCl solution during the dissolution process. To further evaluate the result, the simulation study using Gaussian software was utilized to predict in detail the molecular interaction between NpyCl and CaCO3. The finding from this study showed that the metal complex was formed via ligand after dissolution scale process. Based on the findings, it can be clinched that NpyCl has potential to be used as a scale dissolver in the oilfield, especially in dissolving calcium carbonate scales. © 2022 Penerbit Universiti Kebangsaan Malaysia. All rights reserved.