A Gram-stain-positive, non-endospore-forming, haloalkaliphilic actinobacterium, strain CK5T, was isolated from a soil sample, collected at Cape King (Antarctica), and its taxonomic position was investigated by using a polyphasic approach. Cells were cocci with orange pigmentation, non-motile and grew optimally at 25 °C and pH 9.0-9.5 in the presence of 2 % (w/v) NaCl. Cellular membrane contained MK-7 (72 %), MK-8 (28 %) and anteiso-C15:0 (64.8 %), iso-C16:0 (13.3 %), nC17:0 (9.9 %), n-C16:0 (4.0 %), nC14:0 (3.7 %) as major cellular fatty acids. The DNA G+C content was 64.8 mol%. Strain CK5T, based on the 16S rRNA gene sequence similarity, was most closely related to Nesterenkonia jeotgali strain JG-241T (99.5 %), N. sandarakina YIM 70009T (99.4 %), N. lutea YIM 70081T (99.4 %), N. halotolerans YIM 70084T (99.3 %), N. xinjiangensis YIM 70097T (97.2 %), N. flava CAAS 251T (97.1 %) and N. aethiopica CCUG 48939T (97.1 %). Strain CK5T revealed 31 % DNA-DNA relatedness with respect to Nesternkonia sandarakina DSM 15664T, 29 % with respect to N. jeotgali DSM 19081T, 10 % with respect to N. lutea DSM 15666T and 1 % with respect to N. halotolerans, DSM 15474T, N. xinjiangensis DSM 15475T, N. aethiopica DSM 17733T and N. flava DSM 19422T. Based on the 16S rRNA gene sequences, DNA-DNA hybridization and chemotaxonomic characteristics, strain CK5T represents a novel species of the genus Nesterenkonia, for which the name Nesterenkonia aurantiaca sp. nov. is proposed. The type strain is CK5T (= DSM 27373T = JCM 19723T).