The objective of this study was to measure the intraocular pressure (IOP) using the Kowa HA-2 tonometer in cats. For calibration, a postmortem study was performed in 5 cats, comparing ocular manometry with IOP values measured with the tonometer. To evaluate the accuracy, an in vivo study was performed in 10 anesthetized cats, comparing the ocular manometry with IOP obtained with the tonometer. To validate their outpatient clinical use, IOP measurement study was carried out in 78 healthy eyes, in 7 eyes with clinical signs of glaucoma, and in 20 eyes with clinical signs of uveitis. The correlation coefficient (r²) between manometer and the Kowa HA-2 tonometer was 0.993, and the regression equation was y=0.0878+0,0915x, in the postmortem study. In the in vivo study, the mean IOP in manometry was 15.6±1.1 mm Hg and in tonometry was 15.5±1.2 mm Hg with no statistically significant difference between manometry and tonometry. In the outpatient study of healthy cats, the mean IOP with Kowa HA-2 tonometer was 15.0±1.5, in eyes with clinical signs of glaucoma it was 38.4±8.1 mm Hg, and in eyes with clinical signs of uveitis it was 10.4±2.0 mm Hg. There was a satisfactory correlation and accuracy between the IOP values with manometry and the tonometer. In the outpatient study, the IOP values obtained with the tonometer were consistent for animals with healthy eyes and clinical signs of glaucoma and uveitis. We can conclude that the Kowa HA-2 tonometer is accurate and practical for measuring IOP in cats.