In this paper we investigate partial spreads of H(2n−1, q 2 ) through the related notion of partial spread sets of hermitian matrices, and the more general notion of constant rank-distance sets. We prove a tight upper bound on the maximum size of a linear constant rank-distance set of hermitian matrices over finite fields, and as a consequence prove the maximality of extensions of symplectic semifield spreads as partial spreads of H(2n − 1, q 2 ). We prove upper bounds for constant rank-distance sets for even rank, construct large examples of these, and construct maximal partial spreads of H(3, q 2 ) for a range of sizes.2010 Mathematics Subject Classification. 05B25, 51E23, 51A50, 15A03.