In October 1936 he went to Spain (arriving on 20 October) as a member of the first group of volunteers to fly in the Spanish Civil War.
In Spain, he served in 3^a Escuadrilla, equipped with I-15s.

Two air battles took place on 6 November, at 10:00 and 14:00. In the latter, five Fiats led by capitán Ángel Salas attacked seven ”Chatos” and claimed four victories even if only two claims could be confirmed by ground observers. Salas was thought to have destroyed one machine from a patrol of three, this aircraft trailing smoke as it veered into a cloud and disappeared from sight. Sottotenente Giuseppe Cenni, Tenente Vittor Ugo Ceccherelli and Sottotenente Bernardino Serafini claimed an I-15 each over the Madrid area.
One of the aircraft destroyed was the I-15 flown by leitenant Voronov, who died two days later in hospital from injuries suffered when he crash-landed upon his return to base.
The Nationalist bulletin claimed two aircraft destroyed, while the Government bulletin, which referred only to the earlier engagement, claimed the destruction of two Heinkels, these two most probably claimed by starshiy leitenant Pavel Rychagov, who claimed two enemy aircraft during the day, but it also possible that one of them was claimed by Kovtun (3^a Escuadrilla) who seem to have claimed a victory during the day (according to some sources this was claimed by ramming and thus probably on 13 November when he was killed).
Bonomi confirmed that the Fiats had shot down two fighters, and this was also confirmed by the Air Force communiqué, which admitted the loss of a Fiat and a Junkers. This latter machine was probably flown by Captain Larrauri, who managed to reach Talavera with one engine out of action, the other developing only restricted power, and his aircraft riddled with bullet holes. Von Morau, leader of the Pablos y Pedros squadron, also had to force-land near Madrid at this time.

On 13 November 1936, 14 Fiat CR.32s escorted five ”Junkers” and three ”Romeos”. Over the Paseo de Rosales (Madrid) they were surprised by 16 I-15s led by starshiy leitenant Pavel Rychagov, which dived on them from above out of the sun. Despite immediately being on the defensive, the Fiat pilots managed to protect the bombers as the air battle broke up into a series of individual combats.
The Soviet pilots claimed six victories (three of them fell in Republican territory) while two I-15s were lost when Kovtun and Petr A. Purtov were shot down by Fiats and killed. Kovtun’s death was witnessed by starshiy leitenant Georgiy Zakharov, who also took part in this combat.
On their return flight, the Nationalist pilots encountered five Katiuskas, bombing Getafe and Cuatro Vientos from a height of 5000m. Capitán Ángel Salas damaged one so severely that the crew had to take to their parachutes, and capitán Joaquín García Morato damaged three others.
Totally the CR.32 pilots were credited with ten victories (nine “Curtisses” and one SB). Sergente GianLino Baschirotto (who reported that the I-15 was seen falling out of the sky smoking) and Corrado Ricci were among the Italians to be awarded a “Curtiss” each while Capitano Guido Nobili was credited with a probable. A Soviet fighter, whose pilot escaped by parachute, was shot down by Capitano Goliardo Mosca. The latter was in turn badly wounded in his right thigh and forced to limp back to Talavera, where he crash-landed. Capitano Mariotti force-landed outside the airfield at Getafe, but without damaging his aircraft. Capitán Morato claimed one I-15 (plus three damaged SBs), capitán Salas damaged three I-15s (plus one SB destroyed) and Julio Salvador claimed another I-15.
Capitán Morato recounted:

“Fiat Squadriglia. Bomber escort. “Junkers” and “Romeos” bombing Rosales (Madrid) clashed with 13 “Curtiss fighters”. I shot down one that caught fire in the air, and then machine gunned three “Sophias” till my ammunition ran out. Saw Anti-aircraft fire.
Total flying time 1 hour 30 minutes.”

“Fiat number 128. 1 hour 30 minutes.
Torrijos to Madrid, escorting five Junkers. Fourteen Fiats attacked 13 “Curtiss fighters” – three combats, one frontal, fired on the second while banking, and on the third from behind. Noticed several hits on the fuselage of one aircraft, but could not follow him due to the presence of others. Remained alone throughout, and eventually saw five “Martin bombers” attacking Getafe and Cuatro Vientos from 5000 metres. I fired at them twice until my guns stopped. On landing, Noreña, Celier and Betancour told me that one of the bombers I had attacked lost a wing and fell to the ground, its crew escaping by parachute.”

On 31 December 1936, seven Soviet pilots were decorated with the Gold Star of the Hero of the Soviet Union and the Order of Lenin for their performances in Spain; Vladimir Bocharov (posthumously – KIA on 13 November 1936), Sergey Chernykh, Kovtun (posthumously – KIA on 13 November 1936), Pavel Rychagov, Nikolay Shmelkov, Sergey Tarkhov (posthumously – KIA on 13 November 1936), and Boris Turzhanskii.

At the time of his death, Kovtun was credited with 1 biplane victory.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1936
1	11/06/36		1	Enemy aircraft	Destroyed	I-15		Madrid area	3a Escuadrilla

Biplane victories: 1 destroyed.
TOTAL: 1 destroyed.
(a) Possibly claimed in a ramming on 13 November.

Sources:
Air Aces Home Page - Jan Safarik
Air War over Spain - Jesus Salas Larrazabal, 1974 Ian Allan Ltd, Shepperton, Surrey, ISBN 0-7110-0521-4
Polikarpov I-15, I-16 and I-153 Aces - Mikhail Maslov, 2010 Osprey Publishing, Oxford, ISBN 978-1-84603-981-2