255 Oppavia is a sizeable Main belt asteroid. It was discovered by Austrian astronomer Johann Palisa on 31 March 1886 in Vienna and was named after Opava, a town in the Czech Republic, then part of Austria-Hungary, where Palisa was born. It is orbiting the Sun at a distance of 2.75 AU with an orbital eccentricity (ovalness) of 0.077 and a period of 1662.1 days. The orbital plane is inclined by an angle of 9.47° to the plane of the ecliptic. Photometric observations made during 2013 indicate a synodic rotation period of 19.499 hours with an amplitude of 0.16 in magnitude. The unusual light curve shows three uneven minima and maxima per cycle. In 1995, 255 Oppavia was suggested as a peripheral member of the now defunct Ceres asteroid family, but was found to be an unrelated interloper on the basis of its non-matching spectral type. It classified as a dark X-type asteroid in the Tholen taxonomy.