The aim of this research was analysis of the species composition and planktonic algae biomass in the ponds of Habsburg Park in Żywiec. The urban park ponds have been rarely studied (especially in Poland) so far in this respect. The analyzes of the park ponds water in Żywiec were conducted during the vegetation season in 2016 year, in monthly intervals. The phytoplankton biomass was calculated by comparing the shape of algae to geometrical figures and based on concentrations of the chlorophyll a. The chlorophyll a concentrations and values of the planktonic algae biomass remained at the low level. The species composition showed for dominance of diatoms (i. a. Achnanthes lanceolate (Brébisson ex Kützing) Grun. in Cl. & Grun., Encyonema sp. (Kützing) Krammer). The highest values of the planktonic algae biomass were observed in the summer season. Ponds in the Habsburgs Park in Żywiec have aesthetic and recreational values and therefore more frequent monitoring is necessary.