The intracavity laser absorption spectra (ICLAS) of dideuteroacetylene, C 2 D 2 , and acetylene, C 2 H 2 , have been recorded between 1.03 and 0.99μm with a vertical external cavity surface emitting laser (VECSEL) leading to the observation of seven and six bands, for C 2 D 2 and C 2 H 2 respectively, most of them newly reported. The strong ν 1 +3ν 3 band of C 2 D 2 at 9794.07cm−1 is found accompanied by the two Π–Π hot bands with v 4 =1 and v 5 =1 lower state and by the ν 2 +3ν 3 +2ν 4 band near 9935cm−1. This last band results from an intensity transfer from the ν 1 +3ν 3 band induced by the 1/244 anharmonic interaction. The ν 1 +3ν 3 band of 13C12CD2, present in natural abundance in the sample, could also be detected at 9746.16cm−1 in full agreement with local mode model predictions. The different bands of both C 2 H 2 and C 2 D 2 were found mostly unperturbed and the spectroscopic parameters retrieved from the rovibrational analyses agree satisfactorily with the predictions of the respective effective Hamiltonian models.