Can a 1.2 V rechargeable battery always be used as a replacement?

In many applications, a 1.2 V rechargeable battery can be used without problems.

Although alkaline batteries start at 1.5 V, their voltage quickly drops during use and can eventually fall below the voltage level of a rechargeable battery. Rechargeable batteries such as NiMH batteries provide a much more stable voltage during discharge.

Because of this stable voltage curve, rechargeable batteries perform well in many everyday devices.