The parameters governing the time response of an RCA 1P28 photomultiplier are investigated, and special circuitry for optimum time response is described. Photomultiplier performance is extensively evaluated with respect to application in flash photolysis and pulse radiolysis. The output signal rise time achieved is 360 psec for a light impulse and 540 psec for a step function over a linear range extending to an anode current of 8 mA.