The inaugural trip of the Sud Express took place on 21 October 1887 connecting Lisbon via Madrid to Paris in 45 hours^[8] and services were extended on 4 November 1887 to Calais. For most of the train's history (until 1973), all passengers had to change trains at the French–Spanish border because the two countries used different track gauges, and the break of gauge made it impossible for trains to run through between the two countries.

Initially, the service was weekly, but in 1888 was run twice weekly and from London Charing Cross. Also in 1888, the British Royal Mail launched connecting package services from Lisbon to Rio de la Plata and Brazil.^[9] The service frequency increased further and on 1 January 1907 started to run daily.

In the 1930s, the Spanish Civil War caused the service to be suspended more than once, including from the war's outbreak (in 1936) until 5 November 1937^[10] and again between 11 December 1937^[11] and 1 August 1939. It was again suspended on 1 November 1940 due to World War II. It restarted between Paris and Lisbon in March 1945^[12] and soon also again to Madrid.

The train carried only Pullman cars (luxury-class lounge cars and sleeping cars) until 1933, when first-class cars – a lower class than Pullman – were added.^[5] By at least 1954, it was also carrying some cars with second-class compartments, along with first class and, on the French portion only, Pullman-class cars.^[13] In 1957, Reuters called it "one of Europe's fastest and most famous trains".^[5] By that time, its average speed between Paris and Hendaye had been increased to 105 km/h (65 mph).^[5]

Starting in 1953,^[14]: 62 the Sud Express operated non-stop between Paris and Bordeaux, which in 1964 (at least) was the longest non-stop train journey in the world, covering a distance of 579.0 km (359.8 mi).^[7] Its scheduled average speed in 1964 was 121.0 kilometres per hour (75.2 mph), which at the time was only 15.6 km/h (9.7 mph) slower than the fastest train in all of Europe.^[7] The train's typical consist was long, with up to 17 cars.^[15]

By 1973, the Sud Express's Madrid section had been discontinued,^[6] following the June 1969 introduction of a new train, Puerta del Sol, providing through overnight sleeping-car service between Paris and Madrid.^[16]

However, in 1973, the Sud Express became able to carry through cars over its entire route, now only Paris–Lisbon, thanks to the introduction of couchette cars fitted with variable-gauge wheelsets.^[6] Cooks Continental Timetable explained that, "At Hendaye, the through couchettes Paris–Lisbon and v.v. are jacked up to change the bogies on account of the difference in track gauge between France and Spain." Sitting cars and full sleeping cars continued to run in two separate sections, with passengers having to change at Hendaye or Irun.^[6] Through couchette cars running between Paris and Porto were added in summer 1974,^[17] followed in June 1975 by Paris–Ourense,^[18] the latter being extended to Vigo in 1977.^[19]

A 1939 crash near Tolosa, Spain on 29 March killed, amongst others, the artist Romilly Fedden and his novelist wife Katharine Waldo Douglas.^[20]

On 11 September 1985, a Sud Express train collided head-on with another train near Moimenta-Alcafache station. The locomotives exploded and the train, carrying about 400 passengers, immediately caught fire. Forty-nine deaths were officially confirmed, most caused by the fire, although unofficial estimates put the number of deaths between 100 and 150. A memorial was erected on site.^{[citation needed]}

With the 1994 introduction of LGV Atlantique service from Paris to Irún and from Hendaye (the twin border towns on opposite sides of the French/Spanish border), the through Sud Express service was discontinued in favour of a (faster) combination of two different trains. The original connection from and to Paris was then made with one TGV to Irun and from Hendaye.

The continuing Sud Express ran as a night train from Irun at the French/Spanish border to Lisbon and from Lisbon to Hendaye. Until April 2010, facilities existed for second-class seated accommodation, second-class couchette cars (6-bunk compartments), and first-class private sleeping compartments for 1, 2 or 3 passengers.

Previously, first-class passengers found a bar of chocolate and a small bottle of port in their compartments upon boarding the train, with dinner served in a well-appointed dining and bar car, and a continental breakfast the following morning.^{[citation needed]} However, by 2019 the full restaurant car and catering had been replaced by a cafe-bar car.^[21]

The train consisted of a Talgo IV set hired from Renfe hauled by a RENFE Class 252 between the Irún/Hendaye and Medina del Campo, a RENFE Class 334 between Medina del Campo and Vilar Formoso and a CP Class 5600 between Vilar Formoso and Lisbon.

The Portuguese government's strategic plan for transport, published in October 2011, envisaged the withdrawal of the Sud Express. In October 2012, CP started an Intercity (later downgraded to InterRegional) service between Porto and Coimbra in order to improve the connection between the Sud Express and northern Portugal.^[22] Also from October 2012, this train was operated by CP-Comboios de Portugal.

After 25 April 2018, the southbound Sud Express started at Hendaye (instead of Irún), due to the lack of proper certification from the new fleet of TGV 2N2 operating on the LGV SEA.

The service was suspended on 17 March 2020, due to the COVID-19 pandemic, but has not resumed.^[23][24][25] In March 2021, a representative of the Spanish transport ministry said that the country may stop having night trains even after the end of the coronavirus pandemic.^[26]

• Lists of named passenger trains
• Nord Express