Somatic embryos obtained in vitro are a form of vegetative reproduction that can be used in artificial seed technology, as well as a model to study the principles of plant development. In order to isolate the genes involved in somatic embryogenesis of the cucumber (Cucumis sativus L.), we utilized the suppression subtractive hybridization (SSH). One of the obtained sequences was the CsSEF1 clone (Cucumis sativus Somatic Embryogenesis Zinc Finger 1), with a level of expression that sharply increased with the induction of embryogenesis. The full length cDNA of CsSEF1 encodes the putative 307 amino acid long protein containing three zinc finger motifs, two with CCCH and one with the atypical CHCH pattern. The CsSEF1 protein shows significant similarity to other proteins from plants, in which the zinc fingers arrangement and patterns are very similar. Transcripts of CsSEF1 were localized in the apical part of somatic embryos, starting as early as the polarity was visible and in later developmental stages marking the cotyledon primordia and procambium tissues. As a result of transferring an antisense fragment of CsSEF1 into Arabidopsis thaliana abnormalities in zygotic embryos and also in cotyledons and root development were observed.