High pressure processing (HPP) is an emerging technology that can be used to promote gelation of granules of starchy products. This effect is highly dependent on the nature of the starch and the pressure level applied. This study evaluated the effect of HPP on the granule size of pea starch Particle Size Distribution (PSD) and optical microscopy observation. Samples were processed by HPP up to 600 MPa during 15 minutes at 25ºC, then cooled down quickly, lyophilized and stored before analysed. The microscopy results showed no difference between the samples processed up to 400 MPa. Using polarized light, it was observed the characteristic birefringence pattern ‘maltese-cross’. The sample processed at 500 MPa showed granules at size slightly bigger than unprocessed sample at normal light and, at polarized light, it was verified only few granules with ‘maltese-cross’. The sample processed at 600 MPa showed granules with irregular shapes (differing from every other sample evaluated, which had spherical characteristic shape), and no birefringence pattern, which evidenced the gelatinization induced by the pressure. Also, a slight particle size reduction was observed. The PSD results showed no difference between samples processed up to 400 MPa. At 500 and 600 MPa, an increasing in average particle size was observed, being the biggest particles observed after process at 500 MPa. The distribution of particles at 600 MPa was the broadest of all samples, presenting the smallest and biggest particles among all samples, which is similar to the optical microscopy observations. Results indicated that the pressure firstly induces the granule size increase by forcing water into the granule. After, when the starch is gelatinized, the granule breaks and loses its original form. Those results are important to understand the “cold gelatinization” phenomenon caused by HPP on Pea Starch.