The history of the COMSA Corporation dates back to 1891, the year in which José Miarnau Navás formed a small company to perform railway works. In its early years the company focused on track and station renovation works, quickly gaining a strong reputation with the major rail companies of the time.

In the 1930s the company moved its headquarters from Reus to Barcelona and became a public limited company under the name of Hijos de José Miarnau Navás. Under the leadership of the second generation of the family, it expanded its business throughout Catalonia.

After the Civil War, the company participated in the reconstruction of the country during the 1940s and diversified its activities into other areas of civil engineering, such as the construction of roads, bridges and buildings.

The industrial development that occurred in Catalonia during the following years led to the company participating in major projects like the renovation of the street Calle Aragón and the expansion of the port of Barcelona.

In the late 1950s the third generation of the family took over the reins and in 1964 the company was renamed Construcciones Miarnau. This phase was characterised by the increasing mechanisation of the works, especially those involving railways, a process that the company successfully managed, with the incorporation of specialised machinery.

In the 1960s and 1970s the company consolidated the diversification of its business and began its geographical expansion throughout Spain, first in Madrid and Valencia and later in other areas. Coinciding with this growth, the company was renamed COMSA.

In the following years, COMSA maintained its commitment to technological innovation and in 1982 incorporated the Rapid Track Renewal Train (TRR), which is still unique in Spain and which represented a qualitative leap for the railway projects. In the 1980s the company strengthened its presence throughout the country and at the end of the decade began executing major infrastructure projects.

This led to participation in the construction of the first Spanish high-speed line (Madrid-Seville), inaugurated in 1992 for the Universal Exhibition. In parallel, the company carried out various works related to the Olympic Games in Barcelona, ??most notably the construction of the Palau Sant Jordi.      

The 1990s saw the progressive entry of the fourth generation into the company, while internationalisation began in countries such as Portugal, Argentina and Chile. With the arrival of the new century, COMSA increased its international presence, now operating in ten countries, and diversified its business into activities such as the environment, transport by rail, renewable energy and concessions.

The incorporation of the engineering company EMTE in 2009 allowed the formation of one of the most important infrastructure and engineering groups in Spain. Currently, the COMSA Corporation is present in more than twenty countries and enjoys international recognition, a result of a century of experience in the development of infrastructure, particularly involving railways.