The drying characteristics of Thompson seedless grape (vitis vinifera L.) were investigated using laboratory scale infra-red dryer at four levels of intensity of infra-red radiation (0.861, 0.973, 1.039 and 1.161 kW/m²). The drier was also equipped with three axial flow fans to supply air with at three different temperatures (40, 50 and 60 ^oC) and constant velocity of 2 m/s over the samples to carry the evaporated moisture. The results showed that the moisture content of dried grapes was decreased from (287.15 ±1, %d.b.) to (19.83 – 12.37, % db). It has been found that, both air temperature and infra-red radiation intensity affects rate of drying. Two drying models: Lewis model and Henderson and Pabis's model were examined. The models were compared using the statistical coefficients such as (R), (SE), (χ²), (MBE) and (RMSE). Lewis's model was the best model for describing the drying curves of Thompson seedless grapes. A diffusion model was used to describe the moisture transfer and the effective diffusivity at each drying temperature and radiation intensity. The effective diffusivity ranged from (2.2393x10^-9) to (2.3033x10⁻¹⁰ m²/s) and was significantly affected by radiation intensity. The average value of activation energy was (3.2051 kW/kg). The seedless Thompson grape dried at radiation intensity of (0.973 kW/m²) and air temperature of (60 °C) recorded the highest quality of the dried samples in terms of, total soluble solid, total sugar, reducing sugars and remained Residual sulphur (SO₂).