The aluminum-water reaction is a promising source for hydrogen production. However, experimental studies of this reaction are difficult because of the highly concentrated alkaline solution used to activate the surface of aluminum. Here, we show that the reaction kinetics can be monitored in real time by a Schottky diode sensor, consisting of an ultrathin aluminum film deposited on a semiconductor substrate. Charge resulting from the corrosion of the aluminum film causes an electrical signal in the sensor, which is proportional to the rate of the chemical process. We discuss the possible mechanisms for the reaction-induced charge generation and transfer, as well as the use of Schottky diode based sensors for operando studies of the aluminum-water reaction and similar reactions on metals in concentrated alkaline solutions.