Until recently only two palaemonid species inhabited the southern Baltic: Palaemon adspersus and Palaemonetes varians. Soonafter the year 2000 a new species - Palaemon elegans - arrived and quickly established itself as a new component in the trophicweb. The objects of this research were to define the energy value and energy resources of P. elegans and to compare them withthe corresponding values for the native P. adspersus. These parameters will supply information about this new link in thetrophic web and may help to explain the part played by the new prawn and its population in the energy flow. This work demonstratedthat the energy values of both prawn species were very much the same: the average energy value of P. elegans was16.5±2.1 J mg^-1 DW (19.3±2.5 J mg^-1AFDW) (N = 150), that of P. adspersus was 16.7±2.1 J mg^-1 DW(19.5± 2.5 J mg^-1 AFDW) (N = 71). No statistically significant differences in energy value were found between the two species with respectto sex, size or season. The results show that P. elegans is an energetically valuable food item for predators.Its energy resources in Polish brackish coastal waters can be as high as 150 kJ m^-2; the highest among the palaemonid speciesin this habitat, they constitute a rich supply of food for other organisms.