We report extensive photometry of the dwarf nova V660 Herculis .
During our campaign , lasting from August 2003 to November 2004 , we recorded one bright eruption which turned out to be a superoutburst lasting about 15 days and having amplitude of \sim 4.5 mag .
Clear superhumps with a mean period of P _ { sh } = 0.080924 ( 18 ) days ( 116.53 \pm 0.03 min ) were present during all nights of the superoutburst .
The period of the superhumps was not stable and in the interval covered by our observations it decreased with a rate of \dot { P } / P _ { sh } = -4.0 ( 1.4 ) \times 10 ^ { -5 } .

Basing on our data and the known orbital period of the binary ( Thorstensen and Fenton 2003 ) we calculate the period excess of 3.4 \pm 0.1 % , which is typical for an SU UMa star at this orbital period .
This value indicates that the mass ratio of the system is q = 0.154 .

Key words : Stars : individual : V660 Her – binaries : close – novae , cataclysmic variables