Because of their prebiotic properties, fructo‐oligosaccharides (FOS) that belong to inulin type are known to beneficially affect the host. Among eight commercial tested enzyme preparations, Cytolase PCL5 was found to possess the highest glycosyltransferase activity (7.4 U/ml and 0.17 U/mg proteins). Optimum conditions for FOS production from sucrose were found to be : pH 5.5, temperature 55°C and addition of 7 units of fructosyltransferase activity per gram sucrose. In presence of glucose (competitive inhibitor), the efficiency was 50% based the amount of sucrose consumed. Both HPLC and 13c_nmR spectrometry analysis indicated that synthetised FOS belong to neo‐FOS type (neo‐kestose, neo‐nystose and neo‐fructofuranosylnystose), a structure which is very close to inulin type (same linkage between fructosyl units).