The 26 kDa TBP (TATA-binding protein) interacting protein from the hyperthermophilic archaeon Thermococcus kodakaraensis KOD1 (Tk-TIP26) is a possible transcriptional regulatory protein in Thermococcales. Here, the crystallization of both the native and selenomethionine-substituted proteins and data collection are described. The native crystals belong to the tetragonal space group P4(1)2(1)2 or P4(3)2(1)2, with unit-cell parameters a = 73.83, c = 86.41 A, and diffract to 2.2 A using synchrotron radiation. MAD data was collected and a Bijvoet difference Patterson map showed strong peaks sufficient to determine the positions of the Se atoms.