We investigate a sample of open cluster candidates with no previous age determination using astrometric and photometric data from the Gaia DR2 catalogue. Using proper motions and parallaxes and the full co-variance matrix we determined the astrometric membership probability of the stars in the field of each candidate. The memberships were used as weights in our code based on the cross-entropy global optimization algorithm to fit theoretical isochrones to Gaia photometric data of the open clusters. For 150 open clusters, 49 poorly studied and 101 recently detected, we estimate distances, ages, reddening, and metallicity from the isochrone fits. For the 49 candidates from the New Catalog of Optically Visible Open Clusters and Candidates we also obtain the mean astrometric parameters proper motion, radial velocity, and parallax. The analysis also indicates that 80 candidates are likely not real open clusters.