We present the results of our search for optical counterparts to High Mass X-Ray transient sources. The observations were carried out from the 1.3m telescope of the Skinakas Observatory. We obtained CCD images of the X-ray fields through BVR and Ha filters to identify early-type stars in the R-Ha versus B-V colour-colour diagram. We confirm their nature from their position in near-IR Q vs K diagram constructed using data available from the 2MASS Point Source Catalog. We also obtained medium-resolution spectroscopy of the candidates in order to confirm the presence of Ha emission and perform spectral classification.