We study the problem of answering k -hop reachability queries in a directed graph, i.e., whether there exists a directed path of length k , from a source query vertex to a target query vertex in the input graph. The problem of k -hop reachability is a general problem of the classic reachability (where k=∞ ). Existing indexes for processing classic reachability queries, as well as for processing shortest path distance queries, are not applicable or not efficient for processing k -hop reachability queries. We propose an efficient index for processing k -hop reachability queries. Our experimental results on a wide range of real datasets show that our method is efficient and scalable in terms of both index construction and query processing.