The invention describes a mercury-free high intensity gas-discharge lamp (1) with nominal power in the range of 25 W to 40 W, and in particular with nominal power of 35 W, comprising a quartz glass discharge chamber (2) enclosing a fill gas and comprising a pair of electrodes (3, 4) arranged at opposing ends of the discharge chamber (2) and extending into the discharge chamber (2), for which lamp (1) the capacity of the discharge chamber (2) is greater than or equal to 17 μl and less than or equal to 25 μl; the inner diameter of the discharge chamber (2) is at least 2.3 mm and at most 2.5 mm; the outer diameter of the discharge chamber (2) is at least 5.95 mm and at most 6.15 mm; the thickness of the discharge chamber (2) is at least 3.45 mm and at most 3.85 mm. The fill gas in the discharge chamber (2) of the lamp (1) includes a halide composition comprising sodium iodide NaI and scandium iodide ScI3, whereby the proportion of sodium iodide in the halide composition is at least 62 wt % and at most 76 wt %, and the proportion of scandium iodide in the halide composition is at least 22 wt % and at most 32 wt %. Furthermore, the fill gas comprises xenon gas under a pressure of at least 13 bar in a non-operational state, such that a colour temperature in the range of 3550K to 3850K is attained by the lamp (1) when operated with an initial operating voltage of at least 39V and at most 51V.