In Gram‐negative bacteria, the assembly of outer membrane proteins (OMPs) requires a five‐protein β‐barrel assembly machinery (BAM) complex, of which BamA is an essential and evolutionarily conserved integral outer membrane protein. Here, the refolding, crystallization and preliminary X‐ray crystallographic characterization of the β‐barrel domain of BamA from Escherichia coli (EcBamA) are reported. Native and selenomethionine‐substituted EcBamA proteins were crystallized at 16°C and X‐ray diffraction data were collected to 2.6 and 3.7 Å resolution, respectively. The native crystals belonged to space group P21212, with unit‐cell parameters a = 118.492, b = 159.883, c = 56.000 Å and two molecules in one asymmetric unit; selenomethionine‐substituted protein crystals belonged to space group P4322, with unit‐cell parameters a = b = 163.162, c = 46.388 Å and one molecule in one asymmetric unit. Initial phases for EcBamA β‐barrel domain were obtained from a SeMet SAD data set. These preliminary X‐ray crystallographic studies paved the way for further structural determination of the β‐barrel domain of EcBamA.