A guide for instructors and laboratory assistants to prepare some common aqueous reagents used in an undergraduate laboratory is presented. Dilute reagents consisting of H[superscript +](aq), I[subscript 3][superscript-](aq), Ce[superscript 4+](aq), and Ag[superscript+](aq) were prepared by electrolytic oxidation of respective precursors. Electrolysis was promptly stopped when potassium hydrogen phthalate (KHP) was completely neutralized by OH[superscript -](aq) resulting from an electrolytic reduction of water in the cathode compartment. The neutralization of KHP was monitored by a visual color change of an indicator. The amount of reagent produced in the anode compartment was directly determined from the mass of KHP added to the cathode compartment. The concentrations of reagents determined from the mass of KHP and from an independent volumetric titration were in agreement. The electrolysis cell, powered by an 18 V dc power supply, eliminated the requirement of a coulometer. Setup of an electrolysis cell and experimental details for preparing reagents are presented.