Transition frequencies were determined for transitions in Ra in an atomic beam and for reference lines in Te2 molecules in a vapor cell. The absolute frequencies were calibrated against a GPS stabilized Rb-clock by means of an optical frequency comb. The 7s 2 1 S0(F = 1/2)-7s7p 1 P1(F = 3/2) transition in 225 Ra was determined to be 621 042 124(2) MHz. The measurements provide input for designing efficient and robust laser cooling of Ra atoms in preparation of a search for a permanent electric dipole moment in Ra isotopes. PACS numbers: 31.30.jp, 11.30.Er, 42.62.Fi, Radium (Ra) is the heaviest alkaline earth metal and it offers unique possibilities for measuring parity and time reversal symmetry violation. The particular atomic and nuclear [1][2][3][4][5][6][7][8] structure in Ra isotopes cause the largest enhancement for permanent electric dipole moments (EDMs) [9] in any atom. This arises from the close proximity of the 7s7p 3 P 1 and 7s6d3 D 2 states [1]. The exploitation of the enhancement from this 5 cm −1 separation requires precise knowledge of Ra atomic properties such as the absolute frequencies of transitions that are relevant for laser cooling and state manipulation (see Fig. 1). Many isotopes of Ra are available from radioactive sources such as 229 Th [10-13], or at online isotope production facilities such as ISOLDE, CERN, Switzerland [14,15].A sensitive search for EDMs requires efficient collection of the atoms in an optical trap because of the low abundance of Ra isotopes. A strategy for efficient laser cooling and trapping has been developed with the chemical homologue barium (Ba). Exploiting the strong 6s 2 1 S 0 -6s6p 1 P 1 transition [16,17] resulted in an efficiency of ∼1% for slowing and capturing Ba from an atomic beam, whereas capture efficiencies of below 10 −6 were reported for Ra when using the weak intercombination transition 7sThe optical spectrum of Ra was first studied by Rasmussen [18]. This identified Ra as an alkaline earth metal. Hyperfine splittings and isotope shifts were determined for the 7s 2 1 S 0 -7s7p 1,3 P 1 transitions by collinear laser spectroscopy [14,15] with intense Ra ion beams at ISOLDE, lifetimes of low lying states were determined in ANL, USA [9,19]; no absolute frequencies are quoted.Here we report on a laser spectroscopy measurement of the frequency of the strong 7s 2 1 S 0 -7s7p