Could work, depending on the circuit it is mounted.
When you put electrolytic capacitors (Aluminium, Tantalum, ...) in series
you must put resistors in parallel in order to compensate the leakage
currents (10 times the leakage current value in the resistors) and balance
the transient voltages.
If you don't do that, the first time the voltage is applied to the two caps,
each capacitor won't see the same voltage and the rating may be exceeded.
Shall I remind you that an overloaded capacitor may explode ?

Better to wait for the good value.


"chibitul" a écrit dans le message news:
...
Hi,

I need an electrolytic capacitor, 100V/35uF. I don't have one right
now... can I use two in series, let's say 50V/68uF? The equivalent
capacity should be 34uF, and since they are in series, the maximum
voltage 100V.

Thanks