Abstract Modification of Mg,Al hydrotalcite with Y 3+ prepared following co-precipitation at low suprasaturation led to an improvement of the activity and selectivity for styrene epoxidation with hydrogen peroxide in acetonitrile. The materials were characterized using several techniques such as XRD, DRIFT, TEM, CO 2-TPD and adsorption–desorption isotherms of nitrogen at −196 °C. It was thus demonstrated that the memory effect of hydrotalcite acts very quickly even in an unfriendly environment like that generated by hydrogen peroxide. A direct correlation between the memory effect and the catalytic behavior in the epoxidation of the styrene has been demonstrated. MgO and Al 2O 3 were also prepared using the precipitation method. The investigation of MgO, Al 2O 3 and of a mechanic mixture of them showed that the activity of the catalysts in this reaction correlates very well with their basicity.