Abstract. An integration method based on RKC (Runge-Kutta-Chebyshev) methods is discussed which has been designed to treat moderately stiff and non-stiff terms separately. The method, called PRKC (Partitioned Runge-Kutta-Chebyshev), is a one-step, partitioned Runge-Kutta method of second-order. It belongs to the class of stabilized methods, viz. explicit Runge-Kutta methods possessing extended real stability intervals. The aim of the PRKC method is to reduce the number of function evaluations of the non-stiff terms and to get a non-zero imaginary stability boundary.Key words. Numerical integration of differential equations, Runge-Kutta-Chebyshev methods, Stabilized second-order integration method, Partitioned Runge-Kutta methods AMS subject classifications. 65L20, 65M12, 65M201. Introduction. Stabilized Runge-Kutta methods are explicit methods with extended stability domain along the negative real axis. Their real stability interval has a length proportional to the square of the number of stages. Therefore, these methods are especially suited for the time integration of moderately stiff systems, of large dimension and with eigenvalues known to lie in a long narrow strip along the negative axis. For instance, two-and three-dimensional parabolic partial differential equations (PDE) converted by the method of lines (MOL) give rise to this type of systems. Compared to implicit or IMEX (IMplicit EXplicit) methods, stabilized methods do not require the solution of large linear or nonlinear systems and have a low storage demand. Compared to general explicit methods, they avoid a too severe step size restriction.There exist several stabilized methods. For example, the first-and second-order Runge-Kutta-Chebyshev (RKC) methods [19], the second-and fourth-order Orthogonal-Runge-Kutta-Chebyshev (ROCK) methods [4,1], the third-order DUMKA method [10,13,11], and the second-order Stabilized Explicit Runge-Kutta (SERK2) methods [12]. To be able to treat very stiff reaction terms, [22] proposes to combine the RKC approach with the IMEX idea. A two-step method of this type is discussed in [17], which provides better stability on the imaginary axis. We also wish to mention the essentially optimal explicit Runge-Kutta methods [18] with stability domain containing a given set.In this paper we discuss a one-step, stabilized method of second-order based on the RKC method. The method, called PRKC (Partitioned Runge-Kutta-Chebyshev), treats stiff and non-stiff terms separately. It is devoted to solve systems of ordinary differential equations (ODE) representing space discretization of PDEs aṡ