„Argent above an escutcheon Argent, therein an armed and langued azure lion rampant gules.“ The arms were granted on August 8, 1935. The arms show tower with a gate, which is a canting symbol, the name may have been derived from the Latin "porta" (gate). The gate also appeared on the local seal dating from the early 14th century. The lion is the lion of the Counts of Berg, to which the area belonged in medieval times.
http://www.ngw.nl/heraldrywiki/index.php?title=Porz
Stadler, Klemens; Deutsche Wappen - Bundesrepublik Deutschland. Angelsachsen Verlag, 1972, Band 7 S. 79 Porz am Rhein - Wappen
Wolfgang Pagenstecher redesigned in 1961 by Robert Steimel, Köln-Zollstock