I am trying to issue a named query where one of the bind parameter is a "class".

This would be the same as doing:
select cat
from Cat cat where cat.class = ?1

but when I try to execute the query where the binding as been done with query.setParameter(1, DomesticCat.class)

I first get a INFO log:
INFO [org.hibernate.type.IntegerType] could not bind value 'class test.DomesticCat' to parameter: 1; java.lang.Class cannot be cast to java.lang.Integer

and then the following exception:
java.lang.ClassCastException: java.lang.Class cannot be cast to java.lang.Integer
at org.hibernate.type.IntegerType.set(IntegerType.java:41)
at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:136)
at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:116)
at org.hibernate.param.NamedParameterSpecification.bind(NamedParameterSpecification.java:38)
at org.hibernate.loader.hql.QueryLoader.bindParameterValues(QueryLoader.java:491)....

Is it possible to achieve the binding defined above ?

thanks in advance.

See Hibernate docs Ch 14: "Likewise, the special property class accesses the discriminator value of an instance in the case of polymorphic persistence. A Java class name embedded in the where clause will be translated to its discriminator value."

I believe this means you cannot use a Java Class object as parameter any way. But even the class name wouldn't work as this is only supported if directly embedded. When using a query parameter you have to pass in the discriminator value as defined in the mapping data for the DomesticCat entity.

I had also the same problem and the documentation is totally unclear.
It is expecting an Integer but in the doc they are using String value !!!