Let R be a commutative ring, I(R) be the set of all ideals of R and S be a subset of I * (R) = I(R) \ {0}. We define a Cayley sum digraph of ideals of R, denoted by − − → Cay + (I(R), S ), as a directed graph whose vertex set is the set I(R) and, for every two distinct vertices I and J, there is an arc from I to J, denoted by I −→ J, whenever I + K = J, for some ideal K in S . Also, the Cayley sum graph Cay + (I(R), S ) is an undirected graph whose vertex set is the set I(R) and two distinct vertices I and J are adjacent whenever I + K = J or J + K = I, for some ideal K in S . In this paper, we study some basic properties of the graphs − − → Cay + (I(R), S ) and Cay + (I(R), S ) such as connectivity, girth and clique number. Moreover, we investigate the planarity, outerplanarity and ring graph of Cay + (I(R), S ) and also we provide some characterization for rings R whose Cayley sum graphs have genus one.2010 Mathematics subject classification: primary 05C10; secondary 05C69, 13A15.