The ultraviolet absorption cross sections of methylhydroperoxide, CH3OOH, have been measured over the wavelength range 210 nm to 350 nm at 294 K. We conclude that solar photolysis is a dominant sink for tropospheric CH3OOH. For midlatitudes the photodissociation rate is estimated to be ~4.3¿10-6 s-1 for 0 ¿, 3.7¿10-6 s-1 for 30 ¿, and 1.0¿10-6 s-1 for 70 ¿ zenith angle.