Electronic Journal of Differential Equations, Vol. 2009(2009), No. 25, pp. 1-13. Title: Higher-order linear matrix descriptor differential equations of Apostol-Kolodner type Authors: Grigoris I. Kalogeropoulos (Univ. of Athens, Greece) Athanasios D. Karageorgos (Univ. of Athens, Greece) Athanasios A. Pantelous (City Univ., London, UK) Abstract: In this article, we study a class of linear rectangular matrix descriptor differential equations of higher-order whose coefficients are square constant matrices. Using the Weierstrass canonical form, the analytical formulas for the solution of this general class is analytically derived, for consistent and non-consistent initial conditions. Submitted November 4, 2008. Published February 03, 2009. Math Subject Classifications: 34A30, 34A05, 93C05, 15A21, 15A22. Key Words: Matrix pencil theory; Weierstrass canonical form; linear matrix regular descriptor differential equations