We report the first determination of CP violation parameters from particle-antiparticle asymmetry in the decay of neutral kaons into two charged pions. Observation of such an asymmetry is direct proof of CP violation. A fit to the asymmetry enabled a determination of the parameter-eta+- to be made, yielding the result \eta+-\ = [2.32 +/- 0.14 (stat. ) +/- 0.03 (syst.)] X 10(-3) and phi+- = 42.3-degrees +/- 4.4-degrees (stat.) +/- 0.4-degrees (syst. ), with an additional uncertainty of +/-1.0-degrees due to the error on the present published value of DELTA-m, the K(L)0-K(S)0 mass difference. The magnitudes of both statistical and systematic errors will be significantly reduced in the future. Physics Letters B