Line C is the successor of the narrow gauge railway to Trofa, though it reaches only until ISMAI. In Porto it uses the joint route and then for a short distance shares the tracks with the lines B and E. Line C diverts from line B in Fonte do Cuco, one stop north of Senhora da Hora. Between the stops Custió and Parque da Maia line C diverts from the original route of the narrow gauge railway to join it again at Mandim. This is done to serve better the centre of Maia. Counted from Fonte do Cuco the length is 10 km and there are 10 stops: Cândido dos Reis – Pias – Araújo – Custió – Parque da Maia – Fórum Maia – Zôna Industrial – Mandim – Castelo da Maia – ISMAI. The old narrow gauge railway had on this part four stations and three more on the part which is not realised.
30 July 2005 Estádio do Dragão – Trindade – Senhora da Hora – Fonte do Cuco – Forúm Maia (6.0 km from Fonte do Cuco to Forúm Maia)
31 March 2006 Forúm Maia – ISMAI (4.5 km)
Travel times to ISMAI 23′ from Senhora da Hora, 36′ from Trindade and 41′ from Campanhã. Travel times to Forúm Maia are 9′ less.
Time-table (winter 2021/2022): every 30′, peak hours every 24′, intermediate services until Forúm Maia mo-fr every 30′, peak hours every 24′ resulting in 15′ (12′ during peak hours) over the route until Forum Maia, evenings and weekends no intermediate services.
Nowadays line C has its Porto terminus at Campanhã. When FC Porto is playing line C trams continue to/from Estádio do Dragão.