The effect of a tensile load on the oxidation mechanism of Ni-20Cr alloy was studied between 500 and 900 degreesC by comparison of thin strips oxidised in air under classical conditions and under tensile creep. Simultaneously, the creep behaviour was determined in vacuum and in air. The morphology and the nature of the oxide layers were determined by scanning electron microscopy on cross sections. When applying a tensile load during oxidation, an increase of the oxidation rate occurs. Porosities and microcracks are observed in the NiO layer. Thus, oxygen diffusion is increased via fast diffusion pathes leading at 500 and 600 degreesC to the formation of deep internal oxidation zones and at 900 degreesC to a more extended NiCr2O4 layer. Creep dip tests performed at 500-900 degreesC show an increase of the creep rate at 500 degreesC in air. Beyond this temperature, the mechanical behaviour is the same, whatever the environment. This is attributed to the conjunction of two mechanisms, vacancy injection related to the NiO cationic growth and trapping of these vacancies by chromia either as a continuous film or as internal particles.