  A measurement of the effective $B^0_s\rightarrow K^+K^-$ lifetime is
presented using approximately $37 pb^{-1}$ of data collected by LHCb during
2010. This quantity can be used to put constraints on contributions from
processes beyond the Standard Model in the $B^0_s$ meson system and is
determined by two complementary approaches as $\tau_{B^0_s\to K^+K^-} = 1.440
\pm 0.096 (stat) \pm 0.008 (syst) \pm 0.003 (model) ps$.
