A series of Li-promoted CaO catalysts with Li loadings in the range 0.26–4.0 wt% have been prepared which are effective in the transesterification of glyceryl tributyrate and methanol to methyl butanoate. A Li content of 1.23 wt% provides the optimum activity towards methyl butanoate formation. Li doping increases the base strength of CaO, and XPS and DRIFTS measurements reveal that the optimum loading correlates with the formation of an electron deficient surface Li+ species and associated –OH species at defect sites on the support. High Li loadings result in bulk LiNO3 formation and a drop in surface area and corresponding catalytic activity.