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We compute the principal Lyapunov exponent and Kolmogorov-Sinai(KS) entropyfor Kerr-Newman black hole space-times and investigate the stability andinstability of the equatorial circular geodesics via these exponents. We alsoshow that the principal Lyapunov exponent and KS entropy can be expressed interms of the radial equation of ISCO(innermost stable circular orbit) fortimelike circular geodesics. The other aspect we have studied that among theall possible circular geodesics, which encircle the central black-hole, thetimelike circular geodesics has the longest orbital period i.e. T_{timelike} >T_{photon}, than the null circular geodesics (photon sphere) as measured byasymptotic observers. Thus, the timelike circular geodesics provide the slowestway to circle the Kerr-Newman black-hole. In fact, any stable timelike circulargeodesics other than the ISCO traverses more slowly than the null circulargeodesics.

ISCO, Lyapunov exponent and Kolmogorov-Sinai entropy for Kerr-Newman Black hole