Subshell and process substitution

Apologies if this is a basic question - I'm stuck trying to solve a larger problem, and it's come down to how a shell script is invoked - directly (shellScript.sh) or using sh shellScript.sh. Here's a model for the problem: When I execute on bash: cat <(echo 'Hello') I see the output Hello But when I use: sh -c "cat <(echo 'Hello')" I see errors: sh: -c: line 0: syntax error near unexpected token `(' sh: -c: line 0: `cat <(echo 'Hello')' I've tried escaping the <, ( and ) in various combinations, but I don't see the output anywhere. What am I missing here? My actual problem is that I'm passing a <() as an input argument to a python script within a shell script, and while it works fine when I invoke the shell script using just the name, if I use sh to invoke it, I get errors similar to what I've shown above. Thank you!