Recent observation of several microwave transitions in H _ { 2 } O _ { 2 } from the interstellar medium [ Bergman et al . Astron .
Astrophys. , 531 , L8 ( 2011 ) ] raised interest to this molecule as yet another sensitive probe of the tentative variation of the electron-to-proton mass ratio \mu .
We estimate sensitivity coefficients of the microwave transitions in H _ { 2 } O _ { 2 } to \mu -variation .
The largest coefficient for 14.8 GHz transition is equal to 37 , which is comparable to highest sensitivities in methanol and an order of magnitude higher than sensitivity of the tunneling transition in ammonia .