  We discuss how to construct genuine CP-odd observables at the LHC. We
classify the observables according to the even and odd properties under the
naive T-transformation (\hat{T}). There are two classes of observables of our
interests: CP-odd and \hat{T}-even; CP-odd and \hat{T}-odd. We expect them to
have broad applications to many processes in theories beyond Standard Model
with CP violation. For the purpose of illustration, we use simple example of
W+W- production and subsequent decays at the LHC, where the CP violation
effects are parameterized by effective CP-violating operators of WWZ coupling.
We find significant sensitivity to the CP-odd couplings.
