The calculated distance (air line) between Obrenovac and Sremska Mitrovica is approximately 36 miles respectively 59 kilometers.
By car or train, the actual journey to Sremska Mitrovica is certainly longer, as only the direct route (as the crow flies) between Obrenovac and Sremska Mitrovica has been calculated here.
Air line (approximately)
59 kilometers
32 nautical miles