In this paper, we prove some general convergence theorems for the Picard iteration in cone metric spaces over a solid vector space. As an application, we provide a detailed convergence analysis of the Weierstrass iterative method for computing all zeros of a polynomial simultaneously. These results improve and generalize existing ones in the literature.Keywords: iterative methods, cone metric space, convergence analysis, error estimates, Weierstrass method, polynomial zeros 2000 MSC: 65J15, 54H25, 65H04, 12Y05where T : D ⊂ X → X is an iteration function in a cone metric space (X, d) over a solid vector space (Y, ). Cone metric spaces have a long history (see Collatz [3], Zabrejko [43], Janković, Kadelburg and Radenović [10], Proinov [29] and references therein). For an overview of the theory of cone metric spaces over a solid vector space, we refer the reader to [29] and [31, Section 2].In the second part of the paper, we study the convergence of the famous Weierstrass method [39] for computing all zeros of a polynomial simultaneously. This method was introduced and studied for the first time by Weierstrass in 1891. In 1960-1966, the method was rediscovered by Durand [6] (in Email address: proinov@uni-plovdiv.bg (Petko D. Proinov)