The Gran Telescopio Canarias (GTC) is a 10.4,m segmented telescope that is about to have first light. Science operation will begin in about one year time. In order to ensure that the data coming from the GTC have the required quality and homogeneity and to foster the re-utilization of the data archive, a strategy for an adequate calibration of the data is being implemented. As part of this strategy, a catalogue of standard stars suitable for the photometric calibration of the GTC facility instruments is being put together. The GTC facility instruments are quite versatile and include both broad and narrowband filters plus some tuneable filters, and span the range from the near UV to the mid IR. The GTC Catalogue of Standard Stars that we are producing consists of a number of calibrated stellar fields, which include stars suitable for a 10,m telescope, and are not variable, non-binary and not having infrared excesses if they are to be used in the infrared. The catalogue consists of 30 star fields evenly distributed across the sky. The fields contain sources over the range 12 to 22 magnitude, spanning a wide range of spectral types (A to M) for the visible and near infrared. The stars are being spectro-photometrically calibrated, through the use of spectral templates. This allows selecting the band-passes and thus the calibration magnitudes appropriate for the variety of filters in the GTC facility instruments.