Her keel was laid down on 10 September 1941 by the Deutsche Werft in Hamburg as yard number 340. She was launched on 20 May 1942 and commissioned on 30 July with Kapitänleutnant Hans-Joachim Drewitz in command.
The U-boat's service began with training as part of the 4th U-boat Flotilla on 30 July 1942. She then moved to the 10th flotilla on 1 January 1943 for operations.
German Type IXC/40 submarines were slightly larger than the original Type IXCs. U-525 had a displacement of 1,144 tonnes (1,126 long tons) when at the surface and 1,257 tonnes (1,237 long tons) while submerged.[4] The U-boat had a total length of 76.76 m (251 ft 10 in), a pressure hull length of 58.75 m (192 ft 9 in), a beam of 6.86 m (22 ft 6 in), a height of 9.60 m (31 ft 6 in), and a draught of 4.67 m (15 ft 4 in). The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines producing a total of 4,400 metric horsepower (3,240 kW; 4,340 shp) for use while surfaced, two Siemens-Schuckert 2 GU 345/34 double-acting electric motors producing a total of 1,000 shaft horsepower (1,010 PS; 750 kW) for use while submerged. She had two shafts and two 1.92 m (6 ft) propellers. The boat was capable of operating at depths of up to 230 metres (750 ft).[4]
The submarine had a maximum surface speed of 18.3 knots (33.9 km/h; 21.1 mph) and a maximum submerged speed of 7.3 knots (13.5 km/h; 8.4 mph).[4] When submerged, the boat could operate for 63 nautical miles (117 km; 72 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 13,850 nautical miles (25,650 km; 15,940 mi) at 10 knots (19 km/h; 12 mph). U-525 was fitted with six 53.3 cm (21 in) torpedo tubes (four fitted at the bow and two at the stern), 22 torpedoes, one 10.5 cm (4.13 in) SK C/32 naval gun, 180 rounds, and a 3.7 cm (1.5 in) SK C/30 as well as a 2 cm (0.79 in) C/30 anti-aircraft gun. The boat had a complement of forty-eight.[4]
The submarine's first patrol took her from Kiel on 15 December 1942, across the North Sea and into the Atlantic Ocean through the gap between Iceland and the Faroe Islands. She sank Radhurst on 20 February 1943. The ship went down in three minutes.
She arrived at Lorient in occupied France, on 3 March.
Busch, Rainer; Röll, Hans-Joachim (1999). German U-boat commanders of World War II : a biographical dictionary. Translated by Brooks, Geoffrey. London, Annapolis, Md: Greenhill Books, Naval Institute Press. ISBN1-55750-186-6.
Busch, Rainer; Röll, Hans-Joachim (1999). Deutsche U-Boot-Verluste von September 1939 bis Mai 1945 [German U-boat losses from September 1939 to May 1945]. Der U-Boot-Krieg (in German). Vol. IV. Hamburg, Berlin, Bonn: Mittler. ISBN3-8132-0514-2.
Edwards, Bernard (1996). Dönitz and the Wolf Packs – The U-boats at War. Cassell Military Classics. p. 152. ISBN0-304-35203-9.
Gröner, Erich; Jung, Dieter; Maass, Martin (1991). U-boats and Mine Warfare Vessels. German Warships 1815–1945. Vol. 2. Translated by Thomas, Keith; Magowan, Rachel. London: Conway Maritime Press. ISBN0-85177-593-4.
Kemp, Paul (1997). U-Boats Destroyed – German Submarine Losses in the World Wars. Arms & Armour. ISBN1-85409-515-3.