Qualcosa del genere

codice:
   FILE *fp, *fw;
   char c;

   if((fp = fopen("C:\\test.bin","rb")) == NULL) return 0;
   if((fw = fopen("C:\\out.txt","wb")) == NULL) return 0;

   while((c = fgetc(fp))!=EOF)
         fprintf(fw, "%02X", (unsigned char)c);

   fclose(fw);
   fclose(fp);