Thermochemical ablation (TCA), a novel minimally invasive ablation therapy, was quantitatively evaluated using 23Na MRI at 7T. In this study, eight TCA injection experiments were performed using eight ex vivo bovine liver phantoms. Normalization on the reference tubes and B1-correction of the 23Na images were performed to get quantitative values. This improved the maximum relative error of the estimated amount of substance by a factor of 3.6. The total injected amount was accurately determined. This study shows that quantitative 23Na MRI provides detailed information about TCA injections, which is important for computational modelling of the method and cell damage prediction.