error: expected ‘;’, ‘,’ or ‘)’ before ‘&’ token

I get this error in a C header file in this line :

char * getFechaHora(time_t & tiempoPuro);

In a C source code file i am including the header file and giving the function an implementation

char * getFechaHora(time_t &tiempoPuro){...}

also in my header file i am including correctly the "time.h" library.