From 1876 O'Donovan represented the Daily News during the rising of Bosnia and Herzegovina against the Turks, and in 1879, for the same paper, made his adventurous and famously hazardous journey to Merv. On arrival at Merv, the Turcomans, suspecting him of espionage for the Russians, detained him. The British officer and spy, Lieutenant Colonel C.E. Stewart, who was posing as an Armenian horse trader, expressed surprise that the journalist should be so intrepid, but O'Donovan had told him he was determined to record General Skobelev's troop movements in southern Transcaspia when staying at Mahometabad for weeks. But O'Donovan resolutely decided on watching the Turcomans' stronghold of Geok Tepe, when the Russian advance began. He had negotiated for safe passage when he fell ill, fearing the worst from Persian obstruction. Astutely, O'Donovan refused to reveal Stewart's secret identity to the paper, but events were subsequently released in a book on The Merv Oasis as well as a report to the Royal Geographic Society. In 1881 he was released to greet the Turcomans at Geok Tepe, who were under the impression he was there to assist them.
