Sergio Vallín Loera is a Mexican guitarist of the Mexican band Maná. Vallín was born in Mexico City, where he lived for the first ten years of his life until he moved with his family to Aguascalientes, capital of the state of the same name. Thus he has nicknamed himself "Hidrocálido", after one of the demonyms for his adopted city.

Maná is a Mexican pop rock band formed in 1981. Originally called Sombrero Verde, the current lineup of members is vocalist-guitarist Fher Olvera, drummer Alex González, guitarist Sergio Vallín and bassist Juan Calleros. The band is considered one of the best-selling Latin music artists and the most successful Latin American band of all time with over 25 million records sold worldwide. Moreover, Maná has earned four Grammy Awards, eight Latin Grammy Awards, five MTV Video Music Awards Latin America, six Premios Juventud awards, 19 Billboard Latin Music Awards and 15 Premios Lo Nuestro awards.