A complete classification of 2-arc-transitive dihedrants, that is, Cayley graphs of dihedral groups is given, thus completing the study of these graphs initiated by the third author in [D. Marušič, On 2-arc-transitivity of Cayley graphs, J. Combin. Theory Ser. B 87 (2003) 162-196]. The list consists of the following graphs:(i) cycles C 2n , n 3; (ii) complete graphs K 2n , n 3; (iii) complete bipartite graphs K n,n , n 3; (iv) complete bipartite graphs minus a matching K n,n − nK 2 , n 3; (v) incidence and nonincidence graphs B(H 11 ) and B (H 11 ) of the Hadamard design on 11 points; (vi) incidence and nonincidence graphs B (PG(d, q)) and B (PG(d, q)), with d 2 and q a prime power, of projective spaces; (vii) and an infinite family of regular Z d -covers K 2d q+1 of K q+1,q+1 − (q + 1)K 2 , where q 3 is an odd prime power and d is a divisor of q−1 2 and q − 1, respectively, depending on whether q ≡ 1 (mod 4) or q ≡ 3 (mod 4), obtained by identifying the vertex set of the base graph with two copies of the projective line PG (1, q), where the missing matching consists of all pairs of the form [i, i ], i ∈ PG(1, q), and the edge [i, j ] carries trivial voltage if i = ∞ or j = ∞, and carries voltageh ∈ Z d , the residue class of h ∈ Z, if and only if i − j = θ h , where θ generates the multiplicative group F * q of the Galois field F q .
