Electronic Journal of Differential Equations, Vol. 2012 (2012), No. 11, pp. 1-8. Title: Cauchy-Kowalevski and polynomial ordinary differential equations Authors: Roger J. Thelwell (James Madison Univ., Harrisonburg, VA, USA) Paul G. Warne (James Madison Univ., Harrisonburg, VA, USA) Debra A. Warne (James Madison Univ., Harrisonburg, VA, USA) Abstract: The Cauchy-Kowalevski Theorem is the foremost result guaranteeing existence and uniqueness of local solutions for analytic quasilinear partial differential equations with Cauchy initial data. The techniques of Cauchy-Kowalevski may also be applied to initial-value ordinary differential equations. These techniques, when applied in the polynomial ordinary differential equation setting, lead one naturally to a method in which coefficients of the series solution are easily computed in a recursive manner, and an explicit majorization admits a clear a priori error bound. The error bound depends only on immediately observable quantities of the polynomial system; coefficients, initial conditions, and polynomial degree. The numerous benefits of the polynomial system are shown for a specific example. Submitted October 11, 2010. Published January 17, 2012. Math Subject Classifications: 34A12, 34A34, 35A10. Key Words: Automatic differentiation; power series; Taylor series; polynomial ODE; majorant; error bound.