The Spireites went down to a harsh deflected goal as they fell to their third league defeat in their last four games.
Jerome Taylor bagged the only goal of the encounter to ensure Danny Wilson’s charges ended the year in the Sky Bet League One relegation zone.
The travelling faithful were in full voice as Wilson’s men looked for only their second league win on the road this season.
Due to the four-day turnaround between the crushing 3-0 defeat at Rochdale and the trip to Port Vale, Wilson made three changes.
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Scottish goalkeeper Ryan Fulton returned in place of Lloyd Allison, whilst Jon Nolan and Reece Mitchell replaced Tom Anderson and Connor Dimaio respectively.
Neither side could forge an advantage during a quiet first half under the lights at Vale Park.
The Spireites held the ball for large periods but failed to penetrate the Valiants’ backline, with the hosts content to break up play with mistimed challenges.
The returning Fulton kept out the first chance of the game as he parried
Rigino Cicilia’s effort around the post.
The resultant corner fell to Sam Kelly, who blazed over the bar.
The Spireites should have taken the lead six minutes before the break.
Jay O’Shea’s strike was kept out well by Jak Alnwick with Ched Evans’ backheel from the rebound being scrambled off the line.
Straight after the restart Evans went down inside the box with referee Michael Salisbury waving the visitors’ shouts away.
O’Shea then saw his effort headed clear Nathan Smith before Kjell Knops fired over down the other end.
Cicilia had another shot saved well by Fulton before Thomas broke the deadlock just after the hour.
Thomas picked the ball up out wide, cut inside and bagged his first goal for the Valiants after a Hird deflection beat Fulton.
Mitchell was a constant thorn in the hosts’ side as the Spireites tried to grab something from the game.
He beat a man and pulled the ball back only for the Valiants to clear before he played in O’Shea with Ben Purkiss clearing the danger.
Evans then played in substitute Rai Simons whose shot was valiantly blocked by a hosts’ defender.
The Spireites continued to push for a much-needed point, but they just could not break down the hosts.
In the final few minutes Evans fired an effort wide when he should have done better after cutting inside from the left.
Port Vale: Alnwick, Purkiss, Streete, Smith, Knops, Kelly (Rosa, 89), de Freitas (Amoros 90+4), Grant, Taylor, Cicilia, Thomas (Turner, 88). Unused subs: Pereira, Santos, Shalaj.
Chesterfield: Fulton, Liddle, Hird, Evatt, Donohue, Mitchell (Wilkinson, 74), Nolan, O’Neil, Ariyibi (Simons, 57), O’Shea (Gardner, 84), Evans. Unused subs: Allinson, Anderson, Morrison, Beesley,.
Referee: Michael Salisbury
Attendance: 4,027 (372)