The magnetic properties and magnetic structure are presented for CoPS 3, a quasi-two-dimensional antiferromagnet on a honeycomb lattice with a Néel temperature of K. The compound is shown to have XY-like anisotropy in its susceptibility, and the anisotropy is analysed to extract crystal field parameters. For temperatures between 2 K and 300 K, no phase transitions were observed in the field-dependent magnetization up to 10 Tesla. Single-crystal neutron diffraction shows that the magnetic propagation vector is k= with the moments mostly along the axis and with a small component along the axis, which largely verifies the previously-published magnetic structure for this compound. The magnetic Bragg peak intensity decreases with increasing temperature as a power law with exponent for .