The mod k chromatic index of a graph G is the minimum number of colors needed to color the edges of G in a way that the subgraph spanned by the edges of each color has all degrees congruent to 1 (mod k). Recently, the authors proved that the mod k chromatic index of every graph is at most 198k − 101, improving, for large k, a result of Scott [Discrete Math. 175, 1-3 (1997), 289-291]. Here we study the mod k chromatic index of random graphs. We prove that for every integer k ≥ 2, there is C k > 0 such that if p ≥ C k n −1 log n and n(1−p) → ∞ as n → ∞, then the following holds: if k is odd, then the mod k chromatic index of G(n, p) is asymptotically almost surely equal to k, while if k is even, then the mod k chromatic index of G(2n, p) (respectively G(2n + 1, p)) is asymptotically almost surely equal to k (respectively k + 1).