Orbital and photometric properties of SZ Lyncis

New photometric results based on 3760 observations made on the Johnson BVRI system and 69 new radial-velocity measurements of the large-amplitude Delta Scuti binary SZ Lyncis are reported. Using these data and previous observations from the literature, improved values for the pulsation and orbital parameters are derived. The pulsation period is found to be 0.12052115 days, which is shorter than earlier determinations. The pulsation period is undergoing a secular period change of 3 X 10 to the -12th days/cycle. The orbital period of the binary is found to be 1181.1 days, with an orbital eccentricity of 0.188. A new ephemeris is given, which accurately predicts the times of light maximum and is consistent with the spectroscopic orbit. The mass function is 0.101 solar, which, together with other known properties of SZ Lyn, indicates that the unseen companion is most likely on the main sequence with a spectral type between F2 and K3.