Abstract: 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 ?l and less than or equal to 25 ?l; 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.