Spence shot an eight-under-par 64, a new course record for the Gutenhof Colony Club, to lead the field with Broadhurst three shots behind in joint sixth place.
The target for both men is to carry off the first prize of pounds 41,660 on Sunday to elevate them into ninth place in the Ryder Cup points table.
Points are at stake this week, at the Murphy's English Open and the Volvo German Open during the next fortnight. Then the top nine in the table will be automatically selected for the match with the United States at The Belfry from 24 to 26 September.
Spence, who suffered with shingles for several months earlier this year but is now fit again, said: 'I'm here to win. It is my final throw of the dice.' The 30-year-old from Tunbridge Wells is 16th in the Ryder Cup table with 241,093 points but first place here on Sunday would put him in line to achieve one of his greatest ambitions.
Yesterday, in ideal conditions he had eight birdies and an eagle three at the 18th, his ninth hole, with only two bogeys. Starting at the 10th, he had a wonderful run round the turn from the 17th with four of his birdies and his eagle in five successive holes.
AUSTRIAN OPEN (Vienna) Leading first-round scores (GB or Irl unless stated): 64 J Spence. 65 R Rafferty, P Curry. 66 J Taylor (Aus), D Hospital (Sp). 67 P Broadhurst, P Mitchell, E O'Connell, D Ray, M Clayton (Aus). 68 B Nelson (US), G Turner (NZ), S Torrance, R Boxall, P Mayo, J Bland (SA), M Mackenzie, C Raulerson (US). 69 K Ableidinger (Aut), K Cunningham, E Aubrey (US), T Charnley, B Malley (US), M Poxon, D Williams, J Townsend (US).