The calculated distance (air line) between Ostrów Mazowiecka and Kielce is approximately 144 miles respectively 232 kilometers.
By car or train, the actual journey to Kielce is certainly longer, as only the direct route (as the crow flies) between Ostrów Mazowiecka and Kielce has been calculated here.
Air line (approximately)
232 kilometers
125 nautical miles